sustainability

Article Mapping the Distribution of Water Resource Security in the Beijing-Tianjin- Region at the County Level under a Changing Context

1,2,3, 4, 1, 3,5, 1,6 Xiang Li †, Dongqin Yin †, Xuejun Zhang *, Barry F.W. Croke *, Danhong Guo , Jiahong Liu 1 , Anthony J. Jakeman 3 , Ruirui Zhu 3, Li Zhang 2, Xiangpeng Mu 1, Fengran Xu 1 and Qian Wang 3,7 1 State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Institute of Water Resources and Hydropower Research, Beijing 100038, China; [email protected] (X.L.); [email protected] (D.G.); [email protected] (J.L.); [email protected] (X.M.); [email protected] (F.X.) 2 State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810000, China; [email protected] 3 Fenner School of Environment and Society, Australian National University, Canberra 2601, Australia; [email protected] (A.J.J.); [email protected] (R.Z.); [email protected] (Q.W.) 4 College of Land Science and Technology, China Agricultural University, Beijing 100000, China; [email protected] 5 Mathematical Sciences Institute, Australian National University, Canberra 2601, Australia 6 School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410000, China 7 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Center for Global Change and Water Cycle, Hohai University, 210000, China * Correspondence: [email protected] (X.Z.); [email protected] (B.F.W.C.) These authors contributed equally to this work. †  Received: 8 October 2019; Accepted: 12 November 2019; Published: 16 November 2019 

Abstract: The Beijing-Tianjin-Hebei (Jingjinji) region is the most densely populated region in China and suffers from severe water resource shortage, with considerable water-related issues emerging under a changing context such as construction of water diversion projects (WDP), regional synergistic development, and climate change. To this end, this paper develops a framework to examine the water resource security for 200 counties in the Jingjinji region under these changes. Thus, county-level water resource security is assessed in terms of the long-term annual mean and selected typical years (i.e., dry, normal, and wet years), with and without the WDP, and under the current and projected future (i.e., regional synergistic development and climate change). The outcomes of such scenarios are assessed based on two water-crowding indicators, two use-to-availability indicators, and one composite indicator. Results indicate first that the water resources are distributed unevenly, relatively more abundant in the northeastern counties and extremely limited in the other counties. The water resources are very limited at the regional level, with the water availability per capita and per unit gross domestic product (GDP) being only 279/290 m3 and 46/18 m3 in the current and projected future scenarios, respectively, even when considering the WDP. Second, the population carrying capacity is currently the dominant influence, while economic development will be the controlling factor in the future for most middle and southern counties. This suggests that significant improvement in water-saving technologies, vigorous replacement of industries from high to low water consumption, as well as water from other supplies for large-scale applications are greatly needed. Third, the research identifies those counties most at risk to water scarcity and shows that most of them can be greatly relieved after supplementation by the planned WDP. Finally, more attention should be paid to the southern counties because their water resources are not only limited but also much more sensitive and vulnerable to climate change. This work should benefit water resource management and allocation decisions in the Jingjinji region, and the proposed assessment framework can be applied to other similar problems.

Sustainability 2019, 11, 6463; doi:10.3390/su11226463 www.mdpi.com/journal/sustainability Sustainability 2019, 11, 6463 2 of 24

Keywords: Beijing-Tianjin-Hebei; water resource security; water diversion project; regional synergistic development; climate change

1. Introduction

1.1. The Need for Assessing the Distribution of Water Resource Security under Change The Beijing-Tianjin-Hebei region (i.e., Beijing City, Tianjin City, and Hebei Province), referred to as the Jingjinji region, is considered the heart of China because of its political, economic, cultural, and international significance. At present, significant transformations in the situation related to water resources are taking place or will take place in the Jingjinji region. According to the “Outline of the Synergistic Development Plan for the Beijing-Tianjin-Hebei Region” released in 2015, the regional synergistic development was proposed as the major national strategy for the Jingjinji region. The key feature of this strategy is the coordinated development of Beijing, Tianjin, and Hebei as a whole, aiming at transferring the non-capital core functions and solving the “big city disease” in Beijing by means of adjusting spatial structures of population and industry, expanding environmental capacities, and other measures. Questions on how to evaluate the rationalities of population transfer and industry restructuring to meet the capacities of resources and the environment have therefore been raised [1]. Integrated water resource management is of fundamental importance to guarantee a balance between socio-economic development and environmental conservation, particularly in the Jingjinji region where the imbalance between water demand and supply has existed for long time period. According to the “Outline of the 13th Five-Year Plan for National Economic and Social Development of the People’s Republic of China (2016–2020),” the “Strictest Water Resource Management System” was required to be implemented [2,3], and the city construction, land use, population and industry capacity should all be determined by the local water resources. Questions on how to estimate the water availability within sub-regions and to identify the sensitivity of the water availability to variables such as climate change have therefore been raised [4–7]. To date, several water diversion projects (WDP), such as the South-to-North Water Diversion Project (SNWDP) [8], have been constructed, are currently under construction, or are planned for future construction to import external water to the Jingjinji region for relieving its significant water deficiency. Knowledge of how to allocate the additional water resources from outside the region, and their ability to support the regional synergistic development, are therefore being sought. For the above reasons, it is necessary to explore the distribution of water resources in the Jingjinji region and to reveal the water resource security within sub-regions. This task can largely benefit optimizing water resource allocation, establishing effective coordination mechanisms, and guiding population transfer and industrial restructuring for regional sustainable development.

1.2. Previous Studies on Water Resource Issues Global water resource security is one of the international issues of most concern because it is closely associated with survival of human beings. Oki et al. [9,10] estimated the global hydrological fluxes and assessed the world water resources with both the water availability per year per capita and water scarcity index at a spatial resolution of 0.5 0.5 for the current and future projections. Hanasaki ◦ × ◦ et al. [11,12] developed an integrated model to simulate global water resources at a spatial resolution of 1 1 , which was applied for the water resource assessment with a cumulative withdrawal to demand ◦ × ◦ ratio to locate the water-scarce areas over the world. Wada et al. [13] modelled the global water stress of the recent past at a spatial resolution of 0.5 0.5 using the water scarcity index and taking into ◦ × ◦ account climate variability and growing water demand. Liu and Sun [14] studied the changes in water availability below normal conditions and population impacts in 1.5 ◦C and 2 ◦C warmer worlds at a spatial resolution of 0.5 0.5 over China. ◦ × ◦ Sustainability 2019, 11, 6463 3 of 24

Several studies were carried out with a focus on water resource issues in the Haihe River Basin or the North China Plain within which the Jingjinji region largely falls. Jia et al. [15] developed the Water and Energy Transfer Processes in Large River Basins (WEP-L) model, a distributed hydrological model, to simulate the river runoff in the Haihe River Basin under different scenarios of anthropogenic forcing and climate variability produced by the General Circulation Model (GCM). Qin et al. [16] developed a coupled surface and ground water model in the North China Plain, and found that most of the water loss from the plain can be attributed to the actual evapotranspiration (ET), and thus the key component to be reduced to improve the water use efficiency. Sun et al. [17] applied the Soil and Water Assessment Tool (SWAT) model to assess the surface water resources and ET in the Haihe River Basin, with consideration of the impacts of reservoir operation and agricultural management. Bao et al. [18] used the Variable Infiltration Capacity (VIC) model to distinguish the attribution of climate variability and human activities for the runoff decrease in three small catchments of the Haihe River Basin.

1.3. The Aim of this Paper It should be noted that most studies related to assessment considered the gridded natural runoff as water resources, and these previous studies for the Jingjinji region mostly focused on the quantity and distribution of natural runoff as well as the reasons why the runoff has changed in recent years, suggesting that the issues of water resources in this region for both scientific and socio-economic significance cannot be overemphasized. Little work has been done to map the distribution of water resource security at county level, the smallest administrative unit in China that could better match the requirements of refined water resource management and evaluate the effectiveness of policies and strategies. In particular, both climate change and anthropogenic impacts will impose significant influence for the Jingjinji region, with implementation of the regional synergistic development from the perspective of water demand and the supplementation by the WDP from the perspective of water supply. Actually, the water from the WDP is expected to account for quite a large proportion of supply to the Jingjinji region recently and in the future. Therefore, considering both the natural runoff and water from the WDP is greatly needed for the water resource assessment. This work can help reveal the spatial variability in the capacity of regional water resources in support of socio-economic development among sub-regions and benefit the scientific water resource management and allocation in the Jingjinji region. To fill this gap, this paper proposes an assessment framework to explore the water resource security across 200 counties within the Jingjinji region under the changing context. This is undertaken using modelled, locally (county-level) generated streamflow (i.e., ignoring inflows to each county) and water transferred by the WDP as the total water resource. Groundwater resources are not explicitly considered. The paper proceeds as follows. Section2 describes the study area and the data used for the following analysis. Section3 develops the assessment framework. Section4 presents and discusses the results obtained. Finally, Section5 concludes the paper.

2. Materials

2.1. Study Area The Jingjinji region, located in eastern China, covers a total area of 2.17 105 km2 between × 36◦010–42◦370 N and 113◦040–119◦530 E and accounts for 2.26% of China’s land mass; it largely falls within the Haihe River basin, as shown in Figure1a. Five major tributaries flow into the Haihe River basin, including the Chaobai, Yongding, Daqing, Ziya, and Nanyun rivers. The terrain of the basin is high in the west and low in the east and also includes another major river, the Luanhe River, within the basin to the northeast of Beijing and Tianjin. Plains and mountains (or hills) cover around 40% and 60% of the total area, respectively. The region features a temperate continental monsoon climate. Rapid industrialization, urbanization, a population explosion, and socio-economic development within the Jingjinji region have resulted in disturbances of the water cycles being the strongest Sustainability 2019, 11, 6463 4 of 23

around 40% and 60% of the total area, respectively. The region features a temperate continental Sustainability 2019, 11, 6463 4 of 24 monsoon climate. Rapid industrialization, urbanization, a population explosion, and socio-economic worldwidedevelopment [19–21 within]. The the region Jingjinji is extremely region have thirsty: resulted precipitation in disturbances has decreasedof the water while cycles ET being has increasedthe strongest worldwide [19–21]. The region is extremely thirsty: precipitation has decreased while ET since the 1980s, resulting in a significant reduction in local water resources. The water resources here has increased since the 1980s, resulting in a significant reduction in local water resources. The water have been over-exploited, resulting in a series of environmental problems, such as the drying-up of resources here have been over-exploited, resulting in a series of environmental problems, such as the riverdrying-up reaches, of shrinking river reaches, of wetlands shrinking and of lakes, wetlands severe and water lakes, pollution, severe water decline pollution, of groundwater decline of tables, groundgroundwater subsidence, tables, and ground seawater subsidence, intrusion. and These seaw problemsater intrusion. have These become problems major bottleneckshave become slowing regionalmajor sustainablebottlenecks slowing development regional [22 sustainable–24]. development [22–24]. FigureFigure1b,c 1b,c shows shows all all cities cities and and counties counties in in the the Jingjinji Jingjinjiregion. region. In general, the the county, county, district, district, and county-leveland county-level city (for city simplicity, (for simplicity, referred referred to as county) to as county) are the are third-level the third-level administration administration division in China,division following in China, the following province (firstthe province level) and (first city level) (second and city level). (second The level). main The information main information on all counties in theon all Jingjinji counties region in the is Jingjinji summarized region is in summarized Table1. According in Table 1. to According statistical to data statistical from data 2015, from the total 2015, the total population is 111 million in the entire region, with 21.71, 15.47, and 74.25 million in population is 111 million in the entire region, with 21.71, 15.47, and 74.25 million in Beijing, Tianjin, Beijing, Tianjin, and Hebei, respectively, and the total gross domestic product (GDP) is 6.9 trillion andCNY Hebei, (~1.0 respectively, trillion USD), and with the total2.3, gross1.6, and domestic 3.0 trillion product CNY (GDP in Beijing,) is 6.9 trillionTianjin, CNYand (~1.0Hebei, trillion USD),respectively. with 2.3, In 1.6, total, and there 3.0 trillion are 13 cities CNY or in 200 Beijing, counties Tianjin, (see Table and Hebei,S1 and respectively.Figure S1) in Inthe total, Jingjinji there are 13 citiesregion or to 200 date. counties (see Table S1 and Figure S1) in the Jingjinji region to date.

FigureFigure 1. The1. The Haihe Haihe River River basinbasin and the Jingjinji Jingjinji region. region. (a) (Thea) The Haihe Haihe River River Basin; Basin; (b) Cities (b) Citiesin the in the JingjinjiJingjinji region; region; (c) Counties(c) Counties in thein the Jingjinji Jingjinji region region (the (the red red and and purple purple boundaries boundaries indicate indicate the the Xiong’an NewXiong’an District New and District Tongzhou and Tongzhou District, respectively). District, respectively).

TableTable 1.1. InformationInformation on on counties counties in inthe the Jingjinij Jingjinij region. region.

RegionRegion Beijing BeijingTianjin TianjinHebei HebeiJingjinji Jingjinji Number of Cities 1 1 11 13 Number of Cities 1 1 11 13 Number of Counties 16 16 168 200 NumberTotal of Countiesarea of all 16 16 168 200 16,410 11,946 186,275 214,631 Totalcounties area of all counties 16,410 11,946 186,275 214,631 2 County of Area (km ) 2 9220 9220 Area (km ) County of maximum2229 area (Miyun) 2229 (Miyun) 2270 (Binhai) 2270 (Binhai) 9220 (Weichang) 9220 (Weichang) maximum area (Weichang) (Weichang) County of County of minimum42 area (Dongcheng)42 (Dongcheng) 10 (Heping)10 (Heping) 61 (Yuhua) 61 (Yuhua) 10 (Heping) 10 (Heping) minimum area Total population of all Total 21,705 15,470 74,703 111,878 PopulationPopulation counties population of 21,705 15,470 74,703 111,878 (thousand)(thousand) County of maximum 3955 1240 3955 all counties 2970 (Binhai) population (Chaoyang) () (Chaoyang) County of minimum 308 65 65 349 (Heping) population (Mentougou) (Yingshouyingzi) (Yingshouyingzi) Total GDP of all counties 2065.0 1904.8 2747.5 6717.3 GDP (billion 464.0 CNY Yuan) County of maximum GDP 927.0 (Binhai) 89.1 (Qianan) 927.0 (Binhai) (Chaoyang) 19.2 2.2 2.2 County of minimum GDP 10.7 (Yanqing) (Hongqiao) (Xiahuayuan) (Xiahuayuan) The data of population and GDP is collected for the year 2015; the number of counties is 202 in 2015 and 200 in 2018. GDP—gross domestic product. Sustainability 2019, 11, 6463 5 of 24

2.2. Data Data from multiple sources were collected for this study:

1. A 61-year (1952–2012) long-term land surface hydrologic dataset for China with a 0.25◦ spatial resolution, which was produced by Institute of Geographic Sciences and Natural Resources Research (IGSNRR) of Chinese Academy of Sciences (hereinafter referred to as the IGSNRR dataset, http://hydro.igsnrr.ac.cn/public/vic_outputs.html, which is available in English, and data are freely available), provided estimates of precipitation, actual ET, and runoff. Runoff (or streamflow) is surface plus base flow and is assumed to represent the natural water resources. The actual ET and runoff estimates included in the IGSNRR dataset are derived from the Variable Infiltration Capacity (VIC) model [25] using gridded daily meteorological observations of rainfall, temperature, and wind speed [26]. The model has been shown to be able to reproduce the hydrographs over the major river basins in China, including two representative gauge stations (Luanxian and Guantai) in the Haihe River Basin. Other IGSNRR outputs such as actual ET and soil moisture have also been compared with several observational or observational-based data products to demonstrate their accuracy [26]. 2. The data on water supply, consumption structures and water use efficiency for Beijing, Tianjin, and Hebei during 2000–2017 at provincial level were collected from the “China Water Resources Bulletins (2000–2017),” as shown in Figure2. This paper focuses on the renewable surface and ground water as well as the water from the WDP, which in 2017 accounted, respectively, for 9.1%, 42.0%, and 22.3% of the total water supply in Beijing, 32.4%, 10.2%, and 36.7% in Tianjin, and 25.6%, 47.4%, and 7.2% in Hebei. The agricultural, industrial, domestic, and environmental water consumptions vary greatly among Beijing (12.9%, 8.8%, 46.3%, and 32.1%), Tianjin (38.9%, 20.0%, 22.2%, and 18.9%), and Hebei (69.4%, 11.2%, 14.9%, and 4.5%). 3. The current socio-economic data used in the study were collected from the “Beijing District Statistical Yearbook (2016),” “Beijing Statistical Yearbook (2016),” “Tianjin Statistical Yearbook (2016),” and “Hebei Economic Yearbook (2016).” The future socio-economic scenarios are based on the “Outline of the Thirteenth Five-Year Plans for National Economic and Social Development (2016–2020),” “General Plans for Land Use,” and “General Plans for City” of cities and counties in Beijing, Tianjin, and Hebei (see Section 3.3. for details). The county boundaries were collected from the Geographical Information Monitoring Cloud Platform (http://www.dsac.cn/, which is in Chinese only). 4. The data for major water diversion projects (WDP) were collected from the Bureau of South-to-North Water Transfer of Planning, Design and Management, Ministry of Water Resources, PRC. Table2 summarizes the information on the major WDP to the Jingjinji region, including the current and future scenarios. In general, these WDP take full advantage of the abundant water resources of the Yangtze River and the geographic proximity of the Yellow River, respectively. Water shortages in northern China stimulated China to launch the South-to-North Water Diversion Project (SNWDP), which includes the East, Middle, and West routes. According to the “General Plan on South-to-North Water Diversion Project” and the “Integrated Plan on Haihe River Basin (2012–2030),” the SNWDP will supply a total of 6.15 109 m3 of water to the Jingjinji region in × 2020 through the Middle Route (Phase I) and East Route (Phase II) and 8.58 109 m3 in 2030 × through the Middle Route (Phases I and II) and East Route (Phases II and III). The total water diversion capacities of the WDP will reach 7.4 109 m3 recently and are expected to 12.0 109 m3 × × in the future. It should be noted that only the WDP bringing water into the Jingjinji region from outside the Jingjinji region is considered here, and intra-basin transfers are not considered. These intra-basin transfers have the potential to at least partially compensate for the county level differences noted here, at least for counties impacted by such transfers. Sustainability 2019, 11, 6463 5 of 23

County of maximum 3955 (Chaoyang) 2970 (Binhai) 1240 (Dingzhou) 3955 (Chaoyang) population County of 65 65 minimum 308 (Mentougou) 349 (Heping) (Yingshouyingzi) (Yingshouyingzi) population Total GDP of all 2065.0 1904.8 2747.5 6717.3 counties GDP County of (billion 464.0 (Chaoyang) 927.0 (Binhai) 89.1 (Qianan) 927.0 (Binhai) maximum GDP CNY Yuan) County of 10.7 (Yanqing) 19.2 (Hongqiao) 2.2 (Xiahuayuan) 2.2 (Xiahuayuan) minimum GDP The data of population and GDP is collected for the year 2015; the number of counties is 202 in 2015 and 200 in 2018. GDP—gross domestic product.

2.2. Data Data from multiple sources were collected for this study: 1. A 61-year (1952–2012) long-term land surface hydrologic dataset for China with a 0.25° spatial resolution, which was produced by Institute of Geographic Sciences and Natural Resources Research (IGSNRR) of Chinese Academy of Sciences (hereinafter referred to as the IGSNRR dataset, http://hydro.igsnrr.ac.cn/public/vic_outputs.html, which is available in English, and data are freely available), provided estimates of precipitation, actual ET, and runoff. Runoff (or streamflow) is surface plus base flow and is assumed to represent the natural water resources. The actual ET and runoff estimates included in the IGSNRR dataset are derived from the Variable Infiltration Capacity (VIC) model [25] using gridded daily meteorological observations of rainfall, temperature, and wind speed [26]. The model has been shown to be able to reproduce the hydrographs over the major river basins in China, including two representative gauge stations (Luanxian and Guantai) in the Haihe River Basin. Other IGSNRR outputs such as actual ET and soil moisture have also been compared with several observational or observational-based data products to demonstrate their accuracy [26]. 2. The data on water supply, consumption structures and water use efficiency for Beijing, Tianjin, and Hebei during 2000–2017 at provincial level were collected from the “China Water Resources Bulletins (2000–2017),” as shown in Figure 2. This paper focuses on the renewable surface and ground water as well as the water from the WDP, which in 2017 accounted, respectively, for 9.1%, 42.0%, and 22.3% of the total water supply in Beijing, 32.4%, 10.2%, and 36.7% in Tianjin, and 25.6%, 47.4%, and 7.2% in Hebei. The agricultural, industrial, domestic, and environmental water consumptions vary greatly among Beijing (12.9%, 8.8%, 46.3%, and 2019, , 6463 6 of 24 SustainabilitySustainability32.1%),2019 Tianjin,1111, 6463 (38.9%, 20.0%, 22.2%, and 18.9%), and Hebei (69.4%, 11.2%, 14.9%, and 4.5%).6 of 24

Renewable surface water Renewable groundwater Deep groundwater Agricultural Industrial Domestic Environmental Other water supplies Diverted water 45 45 40 40 ) ) 35

3 35 3 m m 8 30 8 30 25 25 20 20 15 15

Water volume (10 volume Water 10 volume Water (10 10 5 5 0 0 Sustainability 2019, 11, 6463 6 of 23 (a) (b)

Renewable surface water Renewable groundwater Deep groundwater Agricultural Industrial Domestic Environmental Other water supplies Diverted water 30 30

25 25 ) ) 3 3 m m 8 8 20 20 15 15

10 10 Water volume (10 volume Water 5 (10 quantity Water 5

0 0

(c) (d)

Renewable surface water Renewable groundwater Deep groundwater Agricultural Industrial Domestic Environmental Other water supplies Diverted water 250 250

200 ) 200 ) 3 3 m m 8 8 150 150

100 100 Water volume (10 volume Water

50 (10 quantity Water 50

0 0

(e) (f)

Beijing Tianjin Hebei Beijing Tianjin Hebei 350 450 ) 3 ) 3 400 300 350 250 300 200 250

150 200 150 100 100 50 50 Water consumption per capita (m capita per consumption Water 0 (m GDP unit per consumption Water 0

(g) (h)

Figure 2. Water supply, consumption structures, and water use efficiency in the Jingjinji region. (a) Water Figure 2.2. WaterWater supply, supply, consumption consumption structures, structures, and and water water use eusefficiency efficiency in the in Jingjinji the Jingjinji region. region. (a) Water (a) supply in Beijing; (b) Water consumption in Beijing; (c) Water supply in Tianjin; (d) Water consumption supplyWater supply in Beijing; in Beijing; (b) Water (b consumption) Water consumption in Beijing; in (c )Beijing; Water supply (c) Water in Tianjin; supply (d in) Water Tianjin; consumption (d) Water in Tianjin; (e) Water supply in Hebei; (f) Water consumption in Hebei; (g) Water consumption per inconsumption Tianjin; (e) Waterin Tianjin; supply (e) inWater Hebei; supply (f) Water in Hebei; consumption (f) Water in Hebei;consumption (g) Water in consumptionHebei; (g) Water per capita;capita; ( (h)) Water Water consumption consumption per per unit unit GDP.. consumptionh per capita; (h) Water consumptionGDP per unit GDP. 3. The current socio-economic data used in the study were collected from the “Beijing District Statistical Yearbook (2016),” “Beijing Statistical Yearbook (2016),” “Tianjin Statistical Yearbook (2016),” and “Hebei Economic Yearbook (2016).” The future socio-economic scenarios are based on the “Outline of the Thirteenth Five-Year Plans for National Economic and Social Development (2016–2020),” “General Plans for Land Use,” and “General Plans for City” of cities and counties in Beijing, Tianjin, and Hebei (see Section 3.3. for details). The county boundaries were collected from the Geographical Information Monitoring Cloud Platform (http://www.dsac.cn/, which is in Chinese only). 4. The data for major water diversion projects (WDP) were collected from the Bureau of South-to-North Water Transfer of Planning, Design and Management, Ministry of Water Resources, PRC. Table 2 summarizes the information on the major WDP to the Jingjinji region, including the current and future scenarios. In general, these WDP take full advantage of the

Sustainability 2019, 11, 6463 7 of 24

Table 2. Information on the major water diversion projects to the Jingjinji region.

Planning Water No. Project Transfer Capacity Water Intake Area Scenario (109 m3) Middle Route (Phase I) of 4.95 (1.05 to Beijing; , , , 1 South-to-North Water Diversion 0.86 to Tianjin; 3.04 to , , , Current Project Hebei) Beijing, Tianjin Xingtai, Hengshui, , Water Diversion Project from Weishan Langfang, Tianjin, Hengshuihu 2 0.622 Current, Future Station on Yellow River Lake, Baiyangdian Lake (Xiong’an New District) Water Diversion Project from 3 0.8 Tianjin, Cangzhou Current, Future Panzhuang Station on Yellow River Handan, Xingtai, Hengshui, Water Diversion Project from Yellow 4 0.9 Cangzhou, Baoding, Baiyangdian Current, Future River to Baiyangdian Lake in Hebei Lake (Xiong’an New District) Water Diversion Project from Lijiaan 5 0.1 Cangzhou Current, Future Station on Yellow River Middle Route (Phase I, II) of 6.58 (1.49 to Beijing; Handan, Xingtai, Shijiazhuang, 6 South-to-North Water Diversion 0.86 to Tianjin; 4.23 to Baoding, Hengshui, Langfang, Future Project Hebei) Beijing, Tianjin East Route (Phase II, III) of 2.0 (1.0 to Tianjin; 1.0 to 7 South-to-North Water Diversion Hengshui, Cangzhou, Tianjin Future Hebei) Project Water Diversion Project from 8 0.079 Cangzhou Future Xiaokaihe Station on Yellow River Water Diversion Project from 9 0.4 Beijing Future Wanjiazhai Reservoir on Yellow River Handan, Xingtai, Shijiazhuang, Water Diversion Project from 10 0.557 (0.281 to Beijing) Baoding, Langfang, Beijing, Future Xixiayuan Reservoir on Yellow River Tianjin Total in current: 7.372 109 m3; Total in future: 12.038 109 m3. × ×

3. Methodology To assess water resource security and map its spatial distribution at county level in the Jingjinji region, an assessment framework is developed consisting of four major procedures (see Figure3). These are the estimation of total water resources, establishment of assessment indicators, projection (prediction outcomes) of future scenarios, and scenario construction and analysis. For simplicity, the total water resources in a county can be regarded as the sum of natural renewable and anthropogenic waterSustainability resources 2019 of, 11 that, 6463county. 8 of 23

FigureFigure 3. Framework3. Framework for for mappingmapping the distribution distribution of ofwater water resource resource security security at county at county level. level.

3.1. Estimation of Total Water Resources To use the IGSNRR dataset for a county, the following steps are taken: (1) the original 0.25° × 0.25° gridded datasets of daily precipitation, actual ET, and runoff are converted into annual ones; (2) the missing data at the edges of the study area are filled by the moving average method with a window size of 10; (3) all gridded data is subsampled by the nearest neighbor method from 0.25° × 0.25° into 0.01° × 0.01° spatial resolution for application, because the original spatial resolution is too large to be directly used for some small counties; and (4) the newly generated 0.01° × 0.01° gridded data are filtered by the square matrix average method with a window size of 25 × 25; (5) the precipitation, actual ET, and runoff (natural water resources) in each county are the accumulation of the 0.01° × 0.01° gridded data within the county boundary. We have provided details of the downscaling procedure and demonstrated its reliability in the supplementary file (see Figure S2). In this study, allocations of the anthropogenic water resources are derived as follows: (1) the plan for the allocation of water resources to counties of Hebei from the Middle Route (Phase I) of the SNWDP is applied, and that to counties of Beijing and Tianjin from the route is based on the population distribution; (2) the water resources from the other WDP are assumed to be transferred to the counties within the cities, along which the routes of the WDP are built, and also allocated based on the population distribution; and (3) the total water quantities transferred from all the WDP are assumed equal to their planning water diversion capacities. Note that although there are water resources from other supplies in this region, such as from sea water desalination, they are not considered in this paper because of the limited water quantity that can be gained or the requirements for their large-scale production that cannot be met currently.

3.2 Establishment of Assessment Indicators In this study, the concepts of water-crowding and use-to-availability indicators [27,28] are used for measuring the population- and demand-driven water scarcity at the county level, which are widely used because they are simple and intuitive [29]. In general, the water-crowding indicator or

the Falkenmark’s indicator is the water availability per year per capita ( WAPOP ), and the use-to-availability indicator denotes the water scarcity index (WSI), that is, ratio of water withdrawal to availability. Here, with consideration of the GDP-driven water scarcity, the water availability per

unit (10,000 CNY) GDP (WAGDP ) is included also as a water-crowding indicator, and two WSIs are

calculated based on both the population (WSIPOP ) and GDP (WSIGDP ). The indicators are defined as

Sustainability 2019, 11, 6463 8 of 24

3.1. Estimation of Total Water Resources To use the IGSNRR dataset for a county, the following steps are taken: (1) the original 0.25 0.25 ◦ × ◦ gridded datasets of daily precipitation, actual ET, and runoff are converted into annual ones; (2) the missing data at the edges of the study area are filled by the moving average method with a window size of 10; (3) all gridded data is subsampled by the nearest neighbor method from 0.25 0.25 into ◦ × ◦ 0.01 0.01 spatial resolution for application, because the original spatial resolution is too large to ◦ × ◦ be directly used for some small counties; and (4) the newly generated 0.01 0.01 gridded data are ◦ × ◦ filtered by the square matrix average method with a window size of 25 25; (5) the precipitation, × actual ET, and runoff (natural water resources) in each county are the accumulation of the 0.01 0.01 ◦ × ◦ gridded data within the county boundary. We have provided details of the downscaling procedure and demonstrated its reliability in the supplementary file (see Figure S2). In this study, allocations of the anthropogenic water resources are derived as follows: (1) the plan for the allocation of water resources to counties of Hebei from the Middle Route (Phase I) of the SNWDP is applied, and that to counties of Beijing and Tianjin from the route is based on the population distribution; (2) the water resources from the other WDP are assumed to be transferred to the counties within the cities, along which the routes of the WDP are built, and also allocated based on the population distribution; and (3) the total water quantities transferred from all the WDP are assumed equal to their planning water diversion capacities. Note that although there are water resources from other supplies in this region, such as from sea water desalination, they are not considered in this paper because of the limited water quantity that can be gained or the requirements for their large-scale production that cannot be met currently.

3.2. Establishment of Assessment Indicators In this study, the concepts of water-crowding and use-to-availability indicators [27,28] are used for measuring the population- and demand-driven water scarcity at the county level, which are widely used because they are simple and intuitive [29]. In general, the water-crowding indicator or the Falkenmark’s indicator is the water availability per year per capita (WAPOP), and the use-to-availability indicator denotes the water scarcity index (WSI), that is, ratio of water withdrawal to availability. Here, with consideration of the GDP-driven water scarcity, the water availability per unit (10,000 CNY) GDP (WAGDP) is included also as a water-crowding indicator, and two WSIs are calculated based on both the population (WSIPOP) and GDP (WSIGDP). The indicators are defined as

R WA = (1) POP POP R WA = (2) GDP GDP

POP ePOP ePOP WSIPOP = · = (3) R WAPOP

GDP eGDP eGDP WSIGDP = · = (4) R WAGDP where R is the available water resources of a county (with or without the WDP); POP is the population of a county; GDP is the GDP of a county; and ePOP and eGDP are the social water productivities (or water use efficiencies) in terms of water consumptions per capita and per unit GDP. Threshold values to determine the water resource security are set as follows. For WAPOP, the water stress, high water stress, and absolute scarcity occur when the values are below 1700, 1000, and 3 500 m , respectively [9,13,14,29]. For WAGDP, a uniform threshold value cannot be determined because it is closely related to the water consumption (or industry) structure, resulting in big differences among regions. For WSIPOP and WSIGDP, high and extreme stresses occur when the values are over 0.4 and 1 [4,9,12,13,27,30,31]. Sustainability 2019, 11, 6463 9 of 24

With regard to ePOP and eGDP, the observed values of 2017 in Beijing, Tianjin, and Hebei are applied to the respective counties in both current and future scenarios for simplicity; that is, ePOP are 3 3 3 3 3 3 182 m , 176 m , and 242 m , and eGDP are 14 m , 15 m , and 50 m in the counties of Beijing, Tianjin, and Hebei, respectively (eGDP of Hebei is higher than those of Beijing and Tianjin because its dominant water consumption is agricultural use). While considerable improvement in water use efficiency has been made over the past two decades (see Figure2g,h), the scope for future improvements (in an absolute sense) seems limited. Due to the improvement in water use efficiency, the differences in ePOP and eGDP are likely to be significantly reduced also, and the constant values within each sub-region are assumed to reflect well the counties in the Jingjinji region. Moreover, an indicator that reflects the carrying capacity for both population and GDP (composite carrying capacity) is proposed, which can be classified as satisfying the water resource requirements of either “Both,” “Only Population,” “Only GDP,” or “Neither.” The composite indicator is calculated based on the values of the two WSI indicators with respect to their thresholds. The thresholds for both WSIPOP and WSIGDP are set as 0.7 in order to determine which class a county belongs to, allowing for a 30% environmental flow requirement [11,27,28,32]. With the composite indicator, the counties which suffer water scarcity due to the heavy burden of population or GDP can be clearly identified.

3.3. Projection of Future Scenarios on Water Resource Security We consider two future scenarios for discussion—one is under the regional synergistic development, and the other is under climate change. These are the potentially significant factors influencing water resource security throughout the Jingjinji region.

3.3.1. Regional Synergistic Development The principles and methods of prediction on socio-economic development are as follows:

(1) The year 2015 is considered as the current scenario, and the year 2030 as the future scenario, when the regional synergistic development of the Jingjinji region is more mature; (2) The data on population and GDP at county level in the current scenario are collected from the 2015 Statistical Yearbooks of Beijing, Tianjin, and Hebei; (3) The relevant plans of cities or counties are referred to for their target values/growth rates on the population and GDP in/until 2020 and 2030; it should be noted that the plans released after 2015 are used, which consider the regional synergistic development of the Jingjinji region; (4) If a target value/growth rate can be applied for a city from the relevant plans, the future scenario of the city can be predicted, and then the proportional allocation for the future scenario is taken on the basis of the current scenario for the counties within the city; (5) If a county has its target value/growth rate on the population and GDP in/until 2020 and 2030, the value/rate will be applied directly; and otherwise, the growth rates are assumed to be the average growth rate of the city that the county belongs to, and the growth rates of GDP are assumed to be 6.0% during 2020–2030 (which is the long-term annual average target growth rate of GDP set by the Chinese government); (6) In particular, for Beijing City Sub-Center (partial area of Tongzhou District) and Xiong’an New District (which mainly includes , , ) (see Figure1c), the target population and the GDP per area (six main districts of Beijing, that is, Dongcheng, Xicheng, Haidian, Chaoyang, Fengtai, and Shijingshan) are applied in the future scenario.

Figure4 shows the population and GDP of 13 cities in the Jingjinji region in 2015 (current scenario), 2020, and 2030 (future scenario). The total population and GDP are projected as 123.6 million and 19.9 trillion CNY (~2.88 trillion USD) in the future scenario (see Figures S3 and S4 for the current and future distributions of population and GDP). Sustainability 2019, 11, 6463 10 of 23

(2) The data on population and GDP at county level in the current scenario are collected from the 2015 Statistical Yearbooks of Beijing, Tianjin, and Hebei; (3) The relevant plans of cities or counties are referred to for their target values/growth rates on the population and GDP in/until 2020 and 2030; it should be noted that the plans released after 2015 are used, which consider the regional synergistic development of the Jingjinji region; (4) If a target value/growth rate can be applied for a city from the relevant plans, the future scenario of the city can be predicted, and then the proportional allocation for the future scenario is taken on the basis of the current scenario for the counties within the city; (5) If a county has its target value/growth rate on the population and GDP in/until 2020 and 2030, the value/rate will be applied directly; and otherwise, the growth rates are assumed to be the average growth rate of the city that the county belongs to, and the growth rates of GDP are assumed to be 6.0% during 2020–2030 (which is the long-term annual average target growth rate of GDP set by the Chinese government); (6) In particular, for Beijing City Sub-Center (partial area of Tongzhou District) and Xiong’an New District (which mainly includes Xiong County, Rongcheng County, Anxin County) (see Figure 1c), the target population and the GDP per area (six main districts of Beijing, that is, Dongcheng, Xicheng, Haidian, Chaoyang, Fengtai, and Shijingshan) are applied in the future scenario. Figure 4 shows the population and GDP of 13 cities in the Jingjinji region in 2015 (current scenario), 2020, and 2030 (future scenario). The total population and GDP are projected as 123.6 million and 19.9 trillion CNY (~2.88 trillion USD) in the future scenario (see Figures S3 and S4 for the Sustainabilitycurrent and2019 future, 11, 6463 distributions of population and GDP). 10 of 24

2015 (current) 2020 2030 (future) 2015 (current) 2020 2030 (future) 25 6

20 5 4 15 3 10 2 GDP (trillion CNY) (trillion GDP

Population(million) 5 1

0 0

(a) (b)

Figure 4. CurrentCurrent and and future future socio-economic socio-economic deve developmentslopments in inthe the Jingjinji Jingjinji region. region. (a) Population; (a) Population; (b) (GDP.b) GDP .

3.3.2. Climate Change The climateclimate elasticityelasticity ofof runo runoffff [ 33[33,34],34] is is used used to to quantify quantify the the possible possible climate climate change change impacts impacts on theon the runo runoffff across across the the 200 200 counties counties in in the the Jingjinji Jingjinj region.i region. As As recommended recommended in in previousprevious studies,studies, the non-parametric approach to estimate the precipitation elasticity of runoff (εεP) can be written as non-parametric approach to estimate the precipitation elasticity of runoff ( P ) can be written as ! RRRt −R PP εPε==⋅median t− (5) P median  (5) PPPRt −P ·R t− where and are the annual runoff and precipitation and and are the annual mean runoff and where RRt t andP t Pt are the annual runoff and precipitationR and PR and P are the annual mean precipitation.runoff and precipitation. With the estimator With the in estimator Equation (5),in Equa as welltion as (5), the as newly well generatedas the newly data generated for counties data over for 1952–2012,counties over the spatial1952–2012, distribution the spatial of runo distributionff sensitivity of runoff to change sensitivity in precipitation to change at countyin precipitation level across at thecounty Jingjinji level region across can the beJingjinji illustrated. region can be illustrated.

3.4. Scenario Construction and Analysis

For analysis, the long-term annual mean natural water resources are calculated at the county level in the Jingjinji region; as well as for the typical dry (2005), normal (2010), and wet years (2012). These typical years correspond to the exceedance probability of roughly 75%, 50%, and 25%. They are selected on the basis of the historical precipitation (1952–2012) over the Jingjinji region. Current and future scenarios, with or without the WDP, are considered with the assessment indicators (i.e., two water-crowding indicators, two use-to-availability indicators, and one composite indicator). Scenario combinations can therefore be calculated and mapped with the geographic information system (GIS) for analysis and discussion.

4. Results and Discussion

4.1. Quantity and Distribution of Water Resources The precipitation, runoff, and actual ET in the Jingjinji region over 1952–2012 are shown in Figure5. The runoff has been decreasing from the beginning of the period. The annual mean natural water resources are 104 mm (23.6 109 m3), while for the typical dry, normal, and wet years, the water × resources are 72 mm, 86 mm, and 123 mm (16.3 109 m3, 19.5 109 m3, and 27.9 109 m3), respectively. × × × Figure6 shows the spatial distribution of annual mean precipitation, runo ff, actual ET, and runoff coefficient (see Figure S5 for the spatial distribution in the typical years). On average, the annual precipitation, runoff, actual ET, and runoff coefficient have ranges of 336–717 mm, 23–251 mm, 289–601 mm, and 0.05–0.44, respectively. Note that the high runoff coefficient south of Tianjin (38 to 39◦ N, 116.5 to 118◦ E) is due to increased base flow in this region produced by the VIC model. Sustainability 2019, 11, 6463 11 of 23

3.4. Scenario Construction and Analysis For analysis, the long-term annual mean natural water resources are calculated at the county level in the Jingjinji region; as well as for the typical dry (2005), normal (2010), and wet years (2012). These typical years correspond to the exceedance probability of roughly 75%, 50%, and 25%. They are selected on the basis of the historical precipitation (1952–2012) over the Jingjinji region. Current and future scenarios, with or without the WDP, are considered with the assessment indicators (i.e., two water-crowding indicators, two use-to-availability indicators, and one composite indicator). Scenario combinations can therefore be calculated and mapped with the geographic information system (GIS) for analysis and discussion.

4. Results and Discussion

4.1. Quantity and Distribution of Water Resources The precipitation, runoff, and actual ET in the Jingjinji region over 1952–2012 are shown in Figure 5. The runoff has been decreasing from the beginning of the period. The annual mean natural water resources are 104 mm (23.6 × 109 m3), while for the typical dry, normal, and wet years, the water resources are 72 mm, 86 mm, and 123 mm (16.3 × 109 m3, 19.5 × 109 m3, and 27.9 × 109 m3), respectively. Figure 6 shows the spatial distribution of annual mean precipitation, runoff, actual ET, and runoff coefficient (see Figure S5 for the spatial distribution in the typical years). On average, the Sustainabilityannual precipitation,2019, 11, 6463 runoff, actual ET, and runoff coefficient have ranges of 336–717 mm, 23–25111 of 24 mm, 289–601 mm, and 0.05–0.44, respectively. Note that the high runoff coefficient south of Tianjin (38 toFigure 39° N,7 shows116.5 to the 118° annual E) is meandue to natural increased water base resources flow in atthis county region level produced in the Jingjinji by the VIC region model. (see FiguresFigure S6 and 7 shows S12 for the the annual current mean and future natural distributions water reso inurces the typicalat county years). level Table in the3 summarizes Jingjinji region the (see Figures S6 and S12 for the current and future distributions in the typical years). Table 3 characteristic values for different scenarios. The northeastern region has greater natural water resources summarizes the characteristic values for different scenarios. The northeastern region has greater than counties in the other parts of the region. This includes most of the counties in , natural water resources than counties in the other parts of the region. This includes most of the , Tianjin, and Beijing, as well as some of the counties in and Cangzhou. The county counties in Qinhuangdao, Tangshan, Tianjin, and Beijing, as well as some of the counties in Chengde level natural water resources have maximum values of 224 mm, 221 mm (annual mean and dry year and Cangzhou. The county level natural water resources have maximum values of 224 mm, 221 mm for Jinghai of Tianjin), 271 mm (normal year for Qinglong of Qinhuangdao), and 528 mm (wet year (annual mean and dry year for Jinghai of Tianjin), 271 mm (normal year for Qinglong of for Funing of Qinhuangdao). The minimum natural water resources are estimated to be only 36 mm Qinhuangdao), and 528 mm (wet year for Funing of Qinhuangdao). The minimum natural water (annual mean for Wanquan of ), 21 mm (dry year for Luquan of Shijiazhuang), 18 mm resources are estimated to be only 36 mm (annual mean for Wanquan of Zhangjiakou), 21 mm (dry (normal year for Gaoyang of Baoding), and 24 mm (wet year for Raoyang of Hengshui) (noting that year for Luquan of Shijiazhuang), 18 mm (normal year for Gaoyang of Baoding), and 24 mm (wet the minimum water resources for the selected dry year (2005) is higher than the selected normal year year for Raoyang of Hengshui) (noting that the minimum water resources for the selected dry year (2010), due to the different distribution of rainfall). The difference in natural water resources between (2005) is higher than the selected normal year (2010), due to the different distribution of rainfall). The counties can reach around ten times. The natural water resources in over half of the total counties in difference in natural water resources between counties can reach around ten times. The natural the region are below 100 mm (numbers of counties are 114, 155, 143, and 110 for the annual mean and water resources in over half of the total counties in the region are below 100 mm (numbers of typical years). counties are 114, 155, 143, and 110 for the annual mean and typical years).

Precipitation ET Runoff 400 0

300 300

200 600

Runoff Depth(mm) 100 900 Precipiation(mm) Depthand ET slope = -0.97 +- 0.28 0 1200 1952 1962 1972 1982 1992 2002 2012 Ye a r

Figure 5. Precipitation, runoff, and actual evapotranspiration in 1952–2012 in the Jingjinji region. Figure 5. Precipitation, runoff, and actual evapotranspiration in 1952–2012 in the Jingjinji region. After supplementation by the WDP, the total annual mean water resources (natural plus anthropogenic) increase to 135 mm (30.6 109 m3), while for the typical years they increase to × 103 mm, 117 mm, and 154 mm (23.4 109 m3, 26.6 109 m3, and 35.0 109 m3). This corresponds to × × × a relative increase of between 25% (typical wet year) to 44% (typical dry year). In particular, there is an obvious increase in total water resources in the southern and central counties. In terms of the annual mean as well as typical years, the numbers of counties, whose total water resources are below 100 mm, decrease sharply to 36, 91, 73, and 63 (decrease by 68%, 41%, 49%, and 43% in comparison with those without the WDP). Even so, there are still areas whose total water resources are very limited, and these areas shift northward because the water from the WDP is largely diverted to the southern region. The total water resources for the current scenario with the WDP operating at full capacity are 3817 mm, 3824 mm, 3750 mm, and 3891 mm in Heping of Tianjin (a very high population density area) in the annual mean and typical years, respectively. The minimum total water resources are estimated to be 36 mm (annual mean for Wanquan of Zhangjiakou), 22 mm (dry year for Qiaoxi of Zhangjiakou), 40 mm (normal year for Fuping of Baoding), and 27 mm (wet year for Qiaoxi of Zhangjiakou). Sustainability 2019, 11, 6463 12 of 23 SustainabilitySustainability2019 2019,,11 11,, 6463 6463 1212 ofof 2423

. (a) (b) (a) (b)

(c) (d)

Figure 6. Spatial distribution of (annualc) mean precipitation, runoff,(d actual) evapotranspiration, and runoffFigureFigure coefficient 6.6. SpatialSpatial indistributiondistribution the Jingjinji of of region.annual annual mean(a) mean Precipitation; precipit precipitation,ation, (b )runoff, Runoff; runo actualff ,(c actual) Evapotranspiration;evapotranspiration, evapotranspiration, (andd) Runoffandrunoff runo coefficient.coefficientff coefficient in the in theJingjinji Jingjinji region. region. (a) Precipitation; (a) Precipitation; (b) (Runoff;b) Runo (ffc);( Evapotranspiration;c) Evapotranspiration; (d) (Runoffd) Runo coefficient.ff coefficient.

(a) (b) (c) (a) (b) (c) FigureFigure 7. 7. DistributionDistribution of of annual annual mean mean water water re resourcessources at at county level (unit: mm). mm). ( (aa)) Annual Annual mean mean withoutwithoutFigure WDP;7. WDP; Distribution ( (bb)) Annual Annual of annualmean mean with with mean WDP, WDP, water current; resources (c) Annual at county mean level withwith (unit: WDP,WDP, mm). future.future. (a) Annual mean without WDP; (b) Annual mean with WDP, current; (c) Annual mean with WDP, future.

Sustainability 2019, 11, 6463 13 of 24

Table 3. Characteristic values for different scenarios.

Scenario Current Future Annual Annual Typical Year Dry Normal Wet Dry Normal Wet Mean Mean Maximum 224 221 271 528 224 221 271 528 Before Minimum 36 21 18 24 36 21 18 24 Water WDP Jingjinji 104 72 86 123 104 72 86 123 resources (mm) Maximum 3817 3824 3750 3891 5901 5908 5834 5975 After Minimum 36 22 40 27 36 22 48 27 WDP Jingjinji 135 103 117 154 154 122 137 174 Maximum 2089 1263 1777 3149 1955 1182 1639 2948 Before Minimum 3.8 2.6 1.9 5.9 3.0 2.5 1.5 4.6 WDP WAPOP Jingjinji 213 147 176 252 193 133 159 228 (m3) Maximum 2089 1263 1777 3149 1955 1182 1639 2948 After Minimum 35.8 23.8 22.2 28.7 35.2 23.4 21.8 28.2 WDP Jingjinji 279 213 242 318 290 230 257 326 Maximum 792 544 1026 1607 290 199 266 417 Before Minimum 0.2 0.1 0.1 0.3 0.1 0.0 0.0 0.1 WDP WAGDP Jingjinji 35 24 29 42 12 8 10 14 (m3) Maximum 792 544 1026 1607 290 199 266 417 After Minimum 2.2 2.0 2.1 2.3 1.4 1.3 1.3 1.4 WDP Jingjinji 46 35 40 53 18 14 16 20 Maximum 46.66 92.60 94.67 29.87 59.27 95.72 120.25 37.94 Before Minimum 0.12 0.19 0.14 0.08 0.12 0.20 0.15 0.08 WDP Jingjinji 1.04 1.51 1.26 0.88 1.14 1.65 1.38 0.96 WSIPOP Maximum 6.76 10.18 10.91 8.43 6.88 10.35 11.10 8.57 After Minimum 0.12 0.19 0.14 0.08 0.12 0.20 0.15 0.08 WDP Jingjinji 0.79 1.04 0.91 0.70 0.76 0.95 0.85 0.67 Maximum 88.40 120.09 179.36 56.58 238.05 324.19 482.97 152.37 Before Minimum 0.06 0.08 0.05 0.03 0.15 0.23 0.19 0.12 WDP Jingjinji 0.82 1.19 0.99 0.69 2.51 3.65 3.04 2.12 WSIGDP Maximum 6.33 7.89 6.71 6.53 13.82 22.69 16.11 18.79 After Minimum 0.05 0.08 0.05 0.03 0.13 0.18 0.17 0.12 WDP Jingjinji 0.62 0.82 0.72 0.55 1.67 2.10 1.89 1.49 Max. and Min. denote the counties of maximum and minimum values; Jingjinji denotes the whole study area.

4.2. Assessment Based on Current Scenarios The distributions of water resource security are firstly mapped using the assessment indicators in the Jingjinji region for the current scenarios.

4.2.1. Water Availability Per Capita Figure8 shows the distribution of annual mean water availability per capita (see Figure S7 for 3 the distribution in typical years). As shown in Table3, annual mean WAPOP values are 213 m and 3 279 m before and after supplementation by the WDP, taking the Jingjinji region as a whole. WAPOP is larger in the northwest than in the southeast, which are exactly the opposite of the population 3 3 distribution (see Figure S3). The maximum WAPOP can reach 2089 m , 1263 m (annual mean and dry year for Xinglong of Chengde), 1777 m3 (normal year for Qinglong of Qinhuangdao), and 3149 m3 (wet year for Xinglong of Chengde). Before and after supplementation by the WDP, the minimum WAPOP increase from 3.8 m3 (annual mean for Heping of Tianjin), 2.6 m3 (dry year for Qiaoxi of Shijiazhuang), 1.9 m3, and 5.9 m3 (normal and wet years for Heping of Tianjin) to 35.8 m3 (annual mean for Lubei of Tangshan), 23.8 m3 (dry year for Qiaoxi of Zhangjiakou), 22.2 m3 (normal year for Lubei of Tangshan), 3 and 28.7 m (wet year for Qiaoxi of Zhangjiakou). The numbers of counties, whose WAPOP are below 100 m3, reduce drastically from 66, 114, 89, and 82 to 12, 26, 21, and 21, respectively, in terms of the annual mean and typical years after supplementation by the WDP, and they are mainly concentrated in the 6 main districts of Beijing and several counties of Hebei. WAPOP of 36, 24, 27, and 45 counties (18%, Sustainability 2019, 11, 6463 14 of 23

4.2.1 Water Availability Per Capita Figure 8 shows the distribution of annual mean water availability per capita (see Figure S7 for 3 the distribution in typical years). As shown in Table 3, annual mean WAPOP values are 213 m and 3 279 m before and after supplementation by the WDP, taking the Jingjinji region as a whole. WAPOP is larger in the northwest than in the southeast, which are exactly the opposite of the population 3 3 distribution (see Figure S3). The maximum WAPOP can reach 2089 m , 1263 m (annual mean and dry year for Xinglong of Chengde), 1777 m3 (normal year for Qinglong of Qinhuangdao), and 3149 m3 (wet year for Xinglong of Chengde). Before and after supplementation by the WDP, the 3 3 minimum WAPOP increase from 3.8 m (annual mean for Heping of Tianjin), 2.6 m (dry year for Qiaoxi of Shijiazhuang), 1.9 m3, and 5.9 m3 (normal and wet years for Heping of Tianjin) to 35.8 m3 (annual mean for Lubei of Tangshan), 23.8 m3 (dry year for Qiaoxi of Zhangjiakou), 22.2 m3 (normal year for Lubei of Tangshan), and 28.7 m3 (wet year for Qiaoxi of Zhangjiakou). The numbers of 3 counties, whose WAPOP are below 100 m , reduce drastically from 66, 114, 89, and 82 to 12, 26, 21, and 21, respectively, in terms of the annual mean and typical years after supplementation by the Sustainability 2019, 11, 6463 14 of 24 WDP, and they are mainly concentrated in the 6 main districts of Beijing and several counties of

Hebei. WAPOP of 36, 24, 27, and 45 counties (18%, 12%, 13.5%, and 22.5% of the total number) are 3 3 over12%, 1000 13.5%, m and(threshold 22.5%of value the totalof high number) water arestress). over Among 1000 m them,(threshold WAPOP value of only of high 13, water4, 11, and stress). 14 countiesAmong them,(6.5%, WA2%,POP 5.5%,of and only 7% 13, of 4, total 11, andnumber) 14 counties are over (6.5%, 1700 m 2%,3 (threshold 5.5%, and value 7% of of total water number) stress) 3 inare the over annual 1700 mean m (threshold and typical value years, of watereven after stress) supplementation in the annual mean by the and WDP. typical years, even after supplementation by the WDP.

(a) (b)

(c) (d)

Figure 8. DistributionDistribution of of water availability pe perr capita at county level (unit: m3).). ( (aa)) Annual Annual mean, mean, without WDP, current; ( b) Annual mean mean without without WDP, WDP, future; future; ( (cc)) Annual Annual mean mean with with WDP, WDP, current; current; (d) Annual mean with WDP, future.future.

As an application example, the population affected by water scarcity and water deficit under varying thresholds in term of WAPOP can be calculated with the distribution. As shown in Figure9a,b, 3 3 3 3 3 when the thresholds in term of WAPOP are 100 m , 200 m , 300 m , 400 m , and 500 m , before and after supplementation by the WDP, the population affected by water scarcity in the annual mean are decreased from 44.5 million, 82.0 million, 93.2 million, 97.2 million, and 100.1 million to 15.6 million, 56.4 million, 86.6 million, 95.2 million, and 98.9 million, respectively; and the water deficits are decreased from 2.35 billion m3, 9.22 billion m3, 18.00 billion m3, 27.51 billion m3, and 37.41 billion m3 to 0.51 billion m3, 4.32 billion m3, 11.59 billion m3, 20.67 billion m3, and 30.43 billion m3, respectively. Sustainability 2019, 11, 6463 15 of 23

As an application example, the population affected by water scarcity and water deficit under varying thresholds in term of WAPOP can be calculated with the distribution. As shown in Figure 3 3 3 3 3 9a,b, when the thresholds in term of WAPOP are 100 m , 200 m , 300 m , 400 m , and 500 m , before and after supplementation by the WDP, the population affected by water scarcity in the annual mean are decreased from 44.5 million, 82.0 million, 93.2 million, 97.2 million, and 100.1 million to 15.6 million, 56.4 million, 86.6 million, 95.2 million, and 98.9 million, respectively; and the water deficits are decreased from 2.35 billion m3, 9.22 billion m3, 18.00 billion m3, 27.51 billion m3, and 37.41 billion m3 to 0.51 billion m3, 4.32 billion m3, 11.59 billion m3, 20.67 billion m3, and 30.43 billion Sustainabilitym3, respectively.2019, 11 , 6463 15 of 24

Annual mean, Without WDP, Current Annual mean, With WDP, Current Annual mean, Without WDP, Current Annual mean, With WDP, Current Annual mean, Without WDP, Future Annual mean, With WDP, Future Annual mean, Without WDP, Future Annual mean, With WDP, Future 140 45 40 120 35 ) 100 3 m

9 30 80 25

60 20 15 40 Water deficit (10 deficit Water 10 20 5 0 0

Population affected by water scarcity (million) scarcity water by affected Population 100 200 300 400 500 100 200 300 400 500 Threshold in term of water availability per capita (m3) Threshold in term of water availability per capita (m3) (a) (b)

Annual mean, Without WDP, Current Annual mean, With WDP, Current Annual mean, Without WDP, Current Annual mean, With WDP, Current Annual mean, Without WDP, Future Annual mean, With WDP, Future Annual mean, Without WDP, Future Annual mean, With WDP, Future 140 25

120 20 ) 100 3 m 9 80 15

60 10 40 Water deficit (10 deficit Water 5 20

0 0 Population affected by water scarcity (million) scarcity by water affected Population 210.70.4 210.70.4 Threshold in term of water scarcity index Threshold in term of water scarcity index (c) (d)

Figure 9. Population affected by water scarcity and water deficit. (a) Relation between threshold in Figure 9. Population affected by water scarcity and water deficit. (a) Relation between threshold in term of water availability per capita and population affected by water; (b) Relation between threshold term of water availability per capita and population affected by water; (b) Relation between in term of water availability per capita and water deficit; (c) Relation between threshold in term of water threshold in term of water availability per capita and water deficit; (c) Relation between threshold in scarcity index based on population and population affected by water; (d) Relation between threshold in term of water scarcity index based on population and population affected by water; (d) Relation term of water scarcity index based on population and water deficit. between threshold in term of water scarcity index based on population and water deficit. 4.2.2. Water Availability per Unit GDP 4.2.2. Water Availability per Unit GDP Figure 10 shows the distribution of annual mean water availability per unit GDP (see Figure S8 Figure 10 shows the distribution of annual mean water availability per unit GDP (see Figure3 S8 for the distribution in typical years). As shown in Table3, annual mean WAGDP values are 35 m and for the3 distribution in typical years). As shown in Table 3, annual mean WA values are 35 m3 and 46 m for the whole Jingjinji region before and after supplementation by theGDP WDP. WAGDP is larger 3 in46 the m northwestfor the whole than Jingjinji in the southeast,region before which and areafter exactly supplementation the opposite by of the the WDP.GDP distributionWAGDP is larger (see 3 3 Figurein the S3).northwest The maximum than in theWA southeast,GDP can reach which 792 are m exactly, 544 m the(annual opposite mean of andthe dryGDP year distribution for Fengning (see 3 3 of Chengde), 1026 m , and 1607 m (normal and wet3 years3 for Qinglong of Qinhuangdao). Before Figure S3). The maximum WAGDP can reach 792 m , 544 m (annual mean and dry year for Fengning and after supplementation by the WDP, the minimum increase from 0.2 m3 (annual mean for of Chengde), 1026 m3, and 1607 m3 (normal and wet yearsWA GDPfor Qinglong of Qinhuangdao). Before and 3 3 3 Heping of Tianjin), 0.1 m (dry year for Xicheng of Beijing), 0.1 m , and 0.3 m (normal3 and wet years after supplementation by the WDP, the minimum WAGDP increase from 0.2 m (annual mean for for Heping of Tianjin) to 2.2 m3, 2.0 m3, 2.1 m3, and 2.3 m3 (annual mean and three typical years for 3 3 3 Heping of Tianjin), 0.1 m (dry year for Xicheng of Beijing), 0.1 m , and 0.3 m (normal and 3wet years Xicheng of Beijing), respectively. The numbers of counties, whose WAGDP are below 20 m , reduce for Heping of Tianjin) to 2.2 m3, 2.0 m3, 2.1 m3, and 2.3 m3 (annual mean and three typical years for drastically from 51, 70, 68, and 52 to 21, 27, 22, and 16, respectively, in the annual mean and typical years after supplementation by the WDP, mainly concentrated in the main districts of Beijing and Tianjin as well as several counties of Hebei. Sustainability 2019, 11, 6463 16 of 23

3 Xicheng of Beijing), respectively. The numbers of counties, whose WAGDP are below 20 m , reduce drastically from 51, 70, 68, and 52 to 21, 27, 22, and 16, respectively, in the annual mean and typical years after supplementation by the WDP, mainly concentrated in the main districts of Beijing and

TianjinSustainability as well2019 ,as11 ,several 6463 counties of Hebei. 16 of 24

(a) (b)

(c) (d)

FigureFigure 10. 10. DistributionDistribution of of water water availability availability per per unit GDP at county level (unit: m3).). ( (aa)) Annual Annual mean mean withoutwithout WDP, WDP, current; ( bb)) Annual Annual mean mean without without WDP, WDP, future; future; ( (cc)) Annual Annual mean mean with with WDP, WDP, current; current; ((dd)) Annual Annual mean mean with with WDP, WDP, future.

4.2.3.4.2.3. Water Water Scarcity Scarcity Index Based on Population FigureFigure 1111 showsshows the the distribution distribution of of WSI WSI based based on on population with with respect respect to to the the annual mean (see Figure S9 for the distribution in typical years). As shown in Table3, WSI for the whole (see Figure S9 for the distribution in typical years). As shown in Table 3, WSI PPOPOP for the whole Jingjinji region are 1.04 and 0.79 in the annual mean before and after supplementation by the WDP. Jingjinji region are 1.04 and 0.79 in the annual mean before and after supplementation by the WDP. Population-driven water scarcity is the dominant influence for most counties even with the WDP, Population-driven water scarcity is the dominant influence for most counties even with the WDP, which are mainly located in the middle and southern region. The ranges of WSI in the annual which are mainly located in the middle and southern region. The ranges of WSI POP in the annual mean and typical years before and after supplementation by the WDP are narrowedP significantlyOP from mean and typical years before and after supplementation by the WDP are narrowed significantly 0.12–46.66, 0.19–92.60, 0.14–94.67, and 0.08–29.87 to 0.12–6.76, 0.19–10.18, 0.14–10.91, and 0.08–8.43. from 0.12-46.66, 0.19-92.60, 0.14-94.67, and 0.08-29.87 to 0.12-6.76, 0.19-10.18, 0.14-10.91, and The numbers of counties whose WSI are below 1.0 (threshold value of extreme water stress) increase POP WSI 0.08-8.43.from 61, 45, The 56, numbers and 73 to of 91, counties 60, 75, andwhose 94 withoutPOP and are withbelow the 1.0 WDP (threshold in the annual value of mean extreme and typicalwater stress) increase from 61, 45, 56, and 73 to 91, 60, 75, and 94 without and with the WDP in the annual years, respectively. Among them, the numbers of counties whose WSIPOP are below 0.4 (threshold meanvalue ofand high typical water years, stress) respectively. are only 31, Am 19,ong 26, and them, 37 (15.5%,the numbers 9.5%, 13%,of counties and 18.5% whose of total WSI number)POP are belowafter supplementation 0.4 (threshold value by the of WDP.high water stress) are only 31, 19, 26, and 37 (15.5%, 9.5%, 13%, and 18.5%As of antotal application number) after example, supplementation the population by the affected WDP. by water scarcity and water deficit under varyingAs an thresholds application in term example, of WSI thePOP populationcan be calculated affected with by the water distribution. scarcity and As shownwater indeficit Figure under9c,d, varyingwhen the thresholds thresholds in in term term of of WSIWSIPPOPOP canare 2.0,be calculated 1.0, 0.7, and with 0.4, the before distribution. and after As supplementation shown in Figure by the WDP, the population affected by water scarcity in the annual mean are decreased from 53.6 million, 86.6 million, 92.6 million, and 102.3 million to 20.5 million, 67.8 million, 84.5 million, and 100.3 million, respectively; and the water deficits are decreased from 5.57 billion m3, 10.85 billion m3, 13.52 billion m3, and 16.99 billion m3 to 1.00 billion m3, 5.43 billion m3, 9.05 billion m3, and 14.18 billion m3, respectively. Sustainability 2019, 11, 6463 17 of 23

9c,d, when the thresholds in term of WSI POP are 2.0, 1.0, 0.7, and 0.4, before and after supplementation by the WDP, the population affected by water scarcity in the annual mean are decreased from 53.6 million, 86.6 million, 92.6 million, and 102.3 million to 20.5 million, 67.8 million, 84.5 million, and 100.3 million, respectively; and the water deficits are decreased from 5.57 billion m3, 10.85 billion m3, 13.52 billion m3, and 16.99 billion m3 to 1.00 billion m3, 5.43 billion m3, 9.05 3 3 Sustainabilitybillion m , 2019and, 1114.18, 6463 billion m , respectively. 17 of 24

(a) (b)

(c) (d)

Figure 11. Distribution of water scarcity index (WSI) based on population at county level. (a) Annual Figure 11. Distribution of water scarcity index (WSI) based on population at county level. (a) Annual mean without WDP, current; (b) Annual mean without WDP, future; (c) Annual mean with WDP, mean without WDP, current; (b) Annual mean without WDP, future; (c) Annual mean with WDP, current; (d) Annual meanmean withwith WDP,WDP, future.future.

4.2.4.4.2.4 Water Water Scarcity Scarcity Index Index Based Based on on GDPGDP Figure 12 shows the distribution of WSI based on GDP in the annual mean (see Figure S10 for the distributiondistribution inin typical typical years). years). As As shown shown in Tablein Table3, WSI 3, GDPWSIGDPvalues values are0.82 are and0.82 0.62 and for 0.62 the for whole the Jingjinjiwhole Jingjinji region inregion the annual in the mean annual before mean and after before supplementation and after supplementation by the WDP. GDP by-driven the WDP. water scarcityGDP-driven is non-significant water scarcity inis mostnon-significant counties beforein most supplementation counties before supplementation by the WDP, and by it the is further WDP, relieved after supplementation. Ranges of WSI narrow remarkably from 0.06–88.40, 0.08–120.09, and it is further relieved after supplementation.GDP Ranges of WSIGDP narrow remarkably from 0.05–179.36, and 0.03–56.58 to 0.05–6.33, 0.08–7.89, 0.05–6.71, and 0.03–6.53 in the annual mean, and 0.06-88.40, 0.08-120.09, 0.05-179.36, and 0.03-56.58 to 0.05-6.33, 0.08-7.89, 0.05-6.71, and 0.03-6.53 in typical years before and after supplementation by the WDP. The numbers of counties whose WSI the annual mean, and typical years before and after supplementation by the WDP. The numbersGDP of are below 1.0 increase remarkably from 101, 65, 91, and 106 to 145, 125, 129, and 142 without and with counties whose WSI are below 1.0 increase remarkably from 101, 65, 91, and 106 to 145, 125, 129, the WDP in the annualGDP mean and typical years, respectively. Among them, the numbers of counties in and 142 without and with the WDP in the annual mean and typical years, respectively. Among the annual mean and typical years, whose WSI are below 0.4 are 55, 38, 47, and 60 (representing GDP WSI 27.5%,them, the 19%, numbers 23.5%, andof counties 30% of thein the total annual number) mean after and supplementation typical years, whose by the WDP.GDP are below 0.4 are 55, 38, 47, and 60 (representing 27.5%, 19%, 23.5%, and 30% of the total number) after supplementation by the WDP.

Sustainability 2019, 11, 6463 18 of 23 Sustainability 2019, 11, 6463 18 of 24

(a) (b)

(c) (d)

FigureFigure 12.12.Distribution Distribution ofof waterwater scarcityscarcity indexindex (WSI)(WSI) basedbased ononGDP GDPat at county county level. level. ((aa)) AnnualAnnual meanmean withoutwithout WDP,WDP, current; current; ( b(b)) Annual Annual meanmean withoutwithout WDP,WDP, future; future; ((cc)) AnnualAnnual meanmean withwith WDP,WDP, current;current; (d(d)) Annual Annual mean mean with with WDP, WDP, future. future.

4.2.5.4.2.5. CompositeComposite CarryingCarrying CapacityCapacity FigureFigure 13 13 shows shows the the distribution distribution of of composite composite carrying carrying capacity capacity in thein the annual annual mean mean (see (see Figure Figure S11 forS11 the for distribution the distribution in typical in typical years). years). Before Before and after and supplementation after supplementation by the WDP,by the in WDP, both thein both annual the meanannual and mean typical and years,typical very years, few very counties few counties can carry can “Only carry Population”;“Only Population”; several several counties counties can carry can “Onlycarry GDP“Only,” andGDP,” the and numbers the numbers of counties of counties increase significantlyincrease significantly from 26, 14, from 21, and26, 14, 20 to21, 56, and 53, 20 56, to and 56, 51,53, respectively;56, and 51, respectively; the numbers the of numbers counties thatof counties can carry that “Both” can carry increase “Both” slightly increase from slightly 45, 31, from 39, and 45, 5331, to 39, 54, and 37, 53 44, to and 54, 63,37, respectively;44, and 63, respectively; and the numbers and the of numbers counties of that counties can carry that “Neither” can carry obviously“Neither” reduceobviously from reduce 126, 149, from 136, 126, and 149, 123 136, to 86,and 103, 123 95, to and86, 103, 80, respectively.95, and 80, respectively.

(a) (b)

Sustainability 2019, 11, 6463 18 of 23

(a) (b)

(c) (d)

Figure 12. Distribution of water scarcity index (WSI) based on GDP at county level. (a) Annual mean without WDP, current; (b) Annual mean without WDP, future; (c) Annual mean with WDP, current; (d) Annual mean with WDP, future.

4.2.5. Composite Carrying Capacity Figure 13 shows the distribution of composite carrying capacity in the annual mean (see Figure S11 for the distribution in typical years). Before and after supplementation by the WDP, in both the annual mean and typical years, very few counties can carry “Only Population”; several counties can carry “Only GDP,” and the numbers of counties increase significantly from 26, 14, 21, and 20 to 56, 53, 56, and 51, respectively; the numbers of counties that can carry “Both” increase slightly from 45, 31, 39, and 53 to 54, 37, 44, and 63, respectively; and the numbers of counties that can carry “Neither” obviously reduce from 126, 149, 136, and 123 to 86, 103, 95, and 80, respectively. Sustainability 2019, 11, 6463 19 of 24

Sustainability 2019, 11, 6463 19 of 23 (a) (b)

(c) (d)

Figure 13.13. DistributionDistribution of of composite composite carrying carrying capacity capacity at countyat county level. level. (a) Annual (a) Annual mean mean without without WDP, current;WDP, current; (b) Annual (b) meanAnnual without mean WDP,without future; WDP, (c) Annualfuture; ( meanc) Annual with WDP, mean current; with WDP, (d) Annual current; mean (d) withAnnual WDP, mean future. with WDP, future. 4.3. Assessment on Regional Synergistic Development 4.3. Assessment on Regional Synergistic Development The distributions of water resource security in the Jingjinji region are then mapped according to the The distributionsdistributions of of water water resource resource security security in in the the Jingjinji Jingjinji region region are are then then mapped mapped according according to the to assessment indicators arising from projecting the future scenarios of regional synergistic development. assessmentthe assessment indicators indicators arising arising from projecting from projecting the future the scenarios future ofscenarios regional synergisticof regional development. synergistic The mapping of the annual mean is shown in Figures7,8 and 10–13 (see Figures S12–S17 for the Thedevelopment. mapping ofThe the mapping annual of mean the annual is shown mean in Figures is shown7,8 inand Figures 10–13 7, (see 8, 10–13 Figures (see S12–S17 Figures forS12–S17 the distributions in typical years). distributionsfor the distributions in typical in years).typical years). As shown in Table3, the water resources in total (natural plus anthropogenic) increase further to As shownshown inin TableTable3 ,3, the the water water resources resources in in total tota (naturall (natural plus plus anthropogenic) anthropogenic) increase increase further further to 154 mm, 122 mm, 137 mm, and 174 mm (35.0 109 m3, 27.7 109 m3, 31.0 109 m3, and 39.4 109 m3) 154to 154 mm, mm, 122 122 mm, mm, 137 137 mm, mm, and and 174 mm174 mm (35.0 (35.0× 10 ×m 10,9 27.7m3, ×27.710 ×m 10,9 31.0m3, 31.0× 10 × m10,9 andm3, and 39.4 39.4× 10 × m10)9 for the annual mean and typical years, respectively× (corresponding× to relative× increases of 49%,× 70%, form3) the for annualthe annual mean mean and typicaland typical years, years, respectively respective (correspondingly (corresponding to relative to relative increases increases of 49%, of 49%, 70%, 59%, and 41% in comparison to the natural resources). In particular, in Heping of Tianjin, after 59%,70%, 59%, and 41%and 41% in comparison in comparison to the to the natural natural resources). resources). In In particular, particular, in in Heping Heping of of Tianjin,Tianjin, afterafter supplementation by the WDP, the maximum values increase further to 5901 mm, 5908 mm, 5834 mm, supplementationsupplementation byby thethe WDP, WDP, the the maximum maximum values values increase increase further further to 5901to 5901 mm, mm, 5908 5908 mm, mm, 5834 5834 mm, and 5975 mm in the annual mean and typical years. The total water resources in southern counties andmm, 5975 and mm5975 in mm the annualin the annual mean andmean typical and years.typical The years. total The water tota resourcesl water resources in southern in southern counties of the region increase more: the numbers of counties whose total water resources are below 100 mm ofcounties the region of the increase region more:increase the more: numbers the numbers of counties of counties whose total whose water total resources water resources are below are 100 below mm decrease considerably to 21, 40, 36, and 28 (representing relative decrease by 42%, 56%, 51%, and 56% in decrease100 mm decrease considerably considerably to 21, 40, 36,to 21, and 40, 28 36, (representing and 28 (representing relative decrease relative by decrease 42%, 56%, by 51%, 42%, and 56%, 56% 51%, in comparison with the current scenario with the WDP) in the annual mean and typical years, respectively. comparisonand 56% in withcomparison the current with scenario the current with thescenario WDP) inwith the the annual WDP) mean in andthe annual typical years,mean respectively.and typical Taking the Jingjinji region as a whole, the future WA value in the annual mean is estimated years,Taking respectively. the Jingjinji region as a whole, the future WAPOP value in the annual mean is estimated 3 to be 290 m and the future WSIPOP to be 0.76 with the WDP. This represents a slight improvement Taking the Jingjinji region as a whole, the 3future WAPOP value in the annual mean is estimated in comparison with the current WAPOP (279 m3) and WSIPOP (0.79) values; the future WAGDP value 3 POP POP GDP to be 290 m and the future3 WSI POP to be 0.76 with the WDP. This represents a slight improvement is estimated to be 18 m and the future WSIGDP 1.67, which will be much worse than the current in comparison3 with the current WA (279 m3) and WSI (0.79) values; the future WA WAGDP (46 m ) and WSIGDP (0.62) values.POP In comparison with thePOP current scenario with the WDP,GDP the characteristic values of and3 as well as the number of counties within different ranges characteristicvalue is estimated values to of beWA 18POP mand andWSI thePOP futureas well WSI asGDP the 1.67, number which of counties will be withinmuch diworsefferent than ranges the change much less; whereas,3 the characteristic values of WAGDP and WSIGDP as well as the number current WAGDP (46 m ) and WSIGDP (0.62) values. In comparisonGDP with theGDP current scenario with the of counties within different ranges change considerably. In the annual mean and typical years, the of counties within different ranges changeWA considerably.WSI In the annual mean and typical years, the WDP, the characteristic values of POP 3and 3 POP as3 well as the3 number of counties within maximum WAGDP values decrease (to 290 m , 199 m , 266 m , and 417 m ) and the maximum WSIGDP different ranges change much less; whereas, the characteristic values of WA and WSI as values increase substantially (to 13.82, 22.69, 16.11, and 18.79). The numbers of countiesGDP whose WAGDPGDP well as the number of counties within different ranges change considerably. In the annual mean and 3 3 3 3 typical years, the maximum WAGDP values decrease (to 290 m , 199 m , 266 m , and 417 m ) and the

maximum WSIGDP values increase substantially (to 13.82, 22.69, 16.11, and 18.79). The numbers of 3 counties whose WAGDP values are below 20 m increase to 75, 89, 82, and 71 (relative increase by

257%, 230%, 273%, and 344%); and those whose WSIGDP are below 1.0 decrease to 60, 43, 58, and 64 (decrease by 59%, 66%, 55%, and 55%). 3 3 3 As shown in Figure 9, when the thresholds in term of WAPOP are 100 m , 200 m , 300 m , 400 m3, and 500 m3, before and after supplementation by the WDP, the population affected by water scarcity in the annual mean are decreased from 62.2 million, 94.3 million, 104.6 million, 109.2 million, and 111.5 million to 2.4 million, 51.1 million, 91.3 million, 106.9 million, and 110.1 million, respectively; and the water deficits are decreased from 2.89 billion m3, 11.10 billion m3, 21.07 billion

Sustainability 2019, 11, 6463 20 of 24 values are below 20 m3 increase to 75, 89, 82, and 71 (relative increase by 257%, 230%, 273%, and 344%); and those whose WSIGDP are below 1.0 decrease to 60, 43, 58, and 64 (decrease by 59%, 66%, 55%, and 55%). 3 3 3 3 As shown in Figure9, when the thresholds in term of WAPOP are 100 m , 200 m , 300 m , 400 m , 3 andSustainability 500 m 2019, before, 11, 6463 and after supplementation by the WDP, the population affected by water scarcity20 of 23 in the annual mean are decreased from 62.2 million, 94.3 million, 104.6 million, 109.2 million, and 111.5m3, 31.76 million billion to 2.4 m million,3, and 42.80 51.1million, billion 91.3m3 to million, 0.07 billion 106.9 million,m3, 2.70 and billion 110.1 m million,3, 10.35 respectively;billion m3, 20.44 and 3 3 3 3 3 3 thebillion water m deficits, and 31.33 are decreased billion m from, respectively. 2.89 billion When m , 11.10 the billionthresholds m , 21.07in term billion of WSI m ,P 31.76OP are billion 2.0, m1.0,, 3 3 3 3 3 and0.7, 42.80and 0.4, billion before m andto 0.07 after billion supplementation m , 2.70 billion by the m ,WDP, 10.35 the billion population m , 20.44 affected billion by m ,water and 3 31.33scarcity billion in the m annual, respectively. mean are When decreased the thresholds from 74.1 in termmillion, of WSI 96.6POP million,are 2.0, 105.2 1.0, 0.7,million, and 0.4,and before 113.4 andmillion after to supplementation 4.1 million, 64.3 by million, the WDP, 96.6 the million, population and a ff110.8ected million, by water respectively; scarcity in the and annual the meanwater aredeficits decreased are decreased from 74.1 from million, 6.56 96.6 billion million, m3, 105.212.75 million,billion m and3, 15.52 113.4 billion million m to3, 4.1and million, 19.17 billion 64.3 million, m3 to 3 96.60.29 million,billion m and3, 3.64 110.8 billion million, m3, respectively;7.99 billion m and3, and the 14.54 water billion deficits m3 are, respectively. decreased from 6.56 billion m , 3 3 3 3 3 3 12.75In billion comparison m , 15.52 with billion the m current, and 19.17 scenario billion with m tothe 0.29 WDP, billion the m composite, 3.64 billion carrying m , 7.99 capacity billion m of, 3 andfuture 14.54 water billion resources m , respectively. with respect to population improves while the high-speed economic developmentIn comparison in more with extensive the current counties scenario cannot with be the carried WDP, thealthough composite more carrying water is capacity diverted of futureby the waterWDP. resourcesMajor improvements with respect to in population water-saving improves technologies while the (with high-speed particular economic emphasis development on the inagricultural more extensive sector), counties vigorous cannot replacement be carried of industries although from more high water to low is diverted water consumption, by the WDP. as Major well improvementsas water from inother water-saving supplies that technologies can be applied (with particularon a large emphasis scale are ongreatly the agricultural needed to achieve sector), vigorousfurther economic replacement development. of industries from high to low water consumption, as well as water from other supplies that can be applied on a large scale are greatly needed to achieve further economic development. 4.4. Runoff Sensitivity to Climate Change 4.4. Runoff Sensitivity to Climate Change ε Figure 14 shows the distribution of precipitation elasticity of runoff at county level, where P Figure 14 shows the distribution of precipitationε elasticity of runoff at county level, where εP ranges from 1.16 to 3.44. The absolute value of P is relatively large in the northern, western and ranges from 1.16 to 3.44. The absolute value of εP is relatively large in the northern, western and southernsouthern counties,counties, indicating indicating that that the runothe ffrunoffof these of areasthese is moreareas sensitiveis more to sensitive change in to precipitation. change in Particularly,precipitation. much Particularly, more attention much more should attention be paid sh toould the southernbe paid to counties the southern under thecounties climate under change the contextclimate becausechange context of the limited because and of vulnerablethe limited waterand vulnerable resources water in those resources counties. in those counties.

Figure 14. Distribution of precipitation elasticity of runoff at county level. Figure 14. Distribution of precipitation elasticity of runoff at county level.

5. Conclusions To adapt to the significantly changing context, this paper develops an assessment framework to assess water resource security across 200 counties in the Jingjinji region, which is subject to the most serious water resource shortage in China. Major conclusions can be summarized as follows: 1. The distributions of water resources at county level are mapped. The natural water resources (total estimated as 104 mm in the annual mean) are distributed unevenly in the Jingjinji region, exhibiting abundant quantity in the northeastern counties (with a maximum of 224 mm), while

Sustainability 2019, 11, 6463 21 of 24

5. Conclusions To adapt to the significantly changing context, this paper develops an assessment framework to assess water resource security across 200 counties in the Jingjinji region, which is subject to the most serious water resource shortage in China. Major conclusions can be summarized as follows:

1. The distributions of water resources at county level are mapped. The natural water resources (total estimated as 104 mm in the annual mean) are distributed unevenly in the Jingjinji region, exhibiting abundant quantity in the northeastern counties (with a maximum of 224 mm), while there are an extremely limited quantity in the other counties (with a minimum of 36 mm), and over half of the counties have quantity below 100 mm. After supplementation by the current WDP, the annual mean water resources in total are estimated to be 135 mm, with a 30% increase than the natural ones. 2. The distributions of water resource security at county level with two water-crowding indicators are mapped. Both water availability per capita (WAPOP) and per unit (10,000 CNY) GDP (WAGDP) are larger in the northwest than in the southeast counties. Before and after supplementation 3 3 by the WDP, the annual mean WAPOP values are 213 m and 279 m , and annual mean WAGDP 3 values are 35 and 46 m for the whole Jingjinji region, with WAPOP ranging spatially from 3.8 3 3 3 3 (35.8) m to 2089 m and WAGDP ranging from 0.2 (2.2) m to 792 m . 3. The distributions of water resource security at county level with two use-to-availability indicators are mapped. The water scarcity index based on population (WSIPOP) and GDP (WSIGDP) are calculated at county level to determine the distribution of water resource security. Before and after supplementation by the WDP, the annual mean WSIPOP values are 1.04 and 0.79, and annual mean WSIGDP values are 0.82 and 0.62 for the whole Jingjinji region, with WSIPOP ranging spatially from 0.12 to 46.66 (6.76) and WSIGDP ranging from 0.05 to 88.4 (6.33). 4. The distributions of water resource security at county level with one composite indicator are mapped. Whether the water resources can carry the population and GDP at the county level can be identified by the composite carrying capacity (which is classified as “Both,” “Only Population,” “Only GDP,” and “Neither” the water resources can carry). It is observed that in general, the northern counties can carry both population and GDP, the middle and southern counties can carry only GDP or neither of them, indicating that the dominance influence on the carrying capacity is the population in current scenarios. 5. The distributions of water resource security at county level for the regional synergistic development are mapped. The total annual mean water resources (natural plus anthropogenic) increase further to 154 mm, with a 49% increase above the natural resources. The future values of WAPOP 3 3 (290 m ) and WSIPOP (0.76) improve slightly, while the future WAGDP (18 m ) and WSIGDP (1.67) values become worse than the current WAGDP and WSIGDP values for the whole Jingjinji region, which are all distributed unevenly among counties. The carrying capacity of future water resources improves for population. However, it cannot drive the continued high-speed economic development in many middle and southern counties unless there are major improvements in water-saving technologies (with particular emphasis on the agricultural sector) and industries are replaced vigorously from high to low water consumption, as well as water from other supplies needing to be applied on a large scale. 6. The distribution of climate elasticity of runoff at county level is mapped. The runoff is more sensitive and vulnerable in the southern counties, where much more attention should be paid on the issues of water resource security under the climate change context. Sustainability 2019, 11, 6463 22 of 24

These achievements can help policy makers and managers to implement the refined water resource management—(1) locating the counties of water scarcity at different risk levels, (2) estimating the population affected by water scarcity and water deficit, (3) optimizing regional water resources allocation, and evaluating the rationality of route and distribution of planned water diversion projects, (4) determining the carrying capacity of water resources for socio-economic development and guiding population transfer and industrial restructuring for regional synergistic development, and (5) proposing more effective policies and strategies. Because of the applicability, the proposed assessment framework for mapping the distribution of water resource security at county level can also be applied in other similar regions. Future work could beneficially focus on predicting water withdrawals from different sectors of different counties (in place of the social water productivities used in this study), analyze the possible impacts of climate change on the water resources (based on the climate scenarios reported by the Intergovernmental Panel on Climate Change), and further explore the water resource security at county level in this region.

Supplementary Materials: The following are available online at http://www.mdpi.com/2071-1050/11/22/6463/s1. Author Contributions: Conceptualization, X.L. and D.Y.; Methodology, X.L., D.Y., X.Z., B.F.W.C., R.Z. and F.X.; Validation, X.Z., B.F.W.C., R.Z., L.Z., F.X. and Q.W.; Formal analysis, X.L. and D.Y.; Investigation, X.L., D.Y. and D.G.; Resources, J.L. and X.M.; Data curation, X.Z. and D.G.; Writing—original draft preparation, X.L. and D.Y.; Writing—review and editing, X.Z., B.F.W.C. and A.J.J.; Visualization, X.L. and D.Y.; Supervision, J.L.; Project administration, J.L.; Funding acquisition, X.L. and J.L. Funding: This study is supported by the National Key Research and Development Program of China (2016YFC0401401) and the National Natural Science Foundation of China (51609256, 51609122, 51522907, 51739011, and 51569026). Partial support is also from the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology (2017QNRC001). Acknowledgments: The authors would like to thank the editor and two anonymous reviewers for their in-depth reviews and constructive comments, which have led to substantial improvements of the paper. Conflicts of Interest: The authors declare no conflict of interest.

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