Risk Assessment and Pressure Response Analysis of the Water Footprint of Agriculture and Livestock: a Case Study of the Beijing–Tianjin–Hebei Region in China

Home , Changli County, Daming County, Luannan County, Shangyi County, Xinji, Zhuolu County

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Article Risk Assessment and Pressure Response Analysis of the Water Footprint of Agriculture and Livestock: A Case Study of the Beijing–Tianjin–Hebei Region in China

Chen Cao 1,2, Xiaohan Lu 1,2 and Xuyong Li 1,2,*

1 State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 2 University of Chinese Academy of Sciences, Beijing 100049, China * Correspondence: [email protected]; Tel.: +86-10-62849428

Received: 18 June 2019; Accepted: 4 July 2019; Published: 5 July 2019

Abstract: Excessive water consumption, associated with regional agriculture and livestock development and rapid urbanization, has caused significant stress to the ecological health and sustainable use of water resources. We used the water footprint theory to quantify the spatiotemporal characteristics and variation in the water footprint of agriculture and livestock (WF-AL) in the Beijing–Tianjin–Hebei region of China (2000–2016). We predicted the spatial distribution and sustainability of regional water resources at different levels of annual precipitation. Results showed that the average county WF-AL rose from 8.03 108 m3 in 2000 to 10.89 108 m3 in 2016. There was × × spatial heterogeneity compared to the average city WF-AL. The WF-AL varied between the mountains and the plains. The scale of the WF-AL was one of the main reasons for differences in the consumption and distribution of water resources. The development of regional water resources deteriorated from a stable state to an unstable state from 2000 to 2016. Only 5.8% of the areas maintained a stable state of water resources. Even in the predicted wet years, no improvements were found in the instability of water resources in four areas centered on the counties of Xinji, Daming, Luannan, and Weichang. To achieve a medium and long-term balance between WF-AL development and water resource recovery, the WF-AL should be limited and combined with reservoir and cross-regional water transfer.

Keywords: water footprint; the Beijing-Tianjin-Hebei region; agriculture and livestock; water resource

1. Introduction The consumption of freshwater resources is an integral part of modern society but it has gradually become a limiting factor for society [1]. According to the 2017 United Nations World Water Development Report, 60% of the world’s population live in water-deficient areas, and by 2030 the global freshwater demand will grow by 50% compared with current demand [2–4]. China is one of the countries suffering the most severe water shortages worldwide, and problems related to the uneven spatial distribution of water resources and excessive water consumption are extremely serious in this country [5–7]. The Beijing-Tianjin-Hebei (BTH) region in China’s semi-arid and semi-humid areas typifies these problems. In 2017, the BTH region had per capita water resources of 286 m3/person, less than 30% of the international minimum standard [8,9]. Urbanization of the BTH region has reached 64.9%, and 2.35% of the land area has to bear 7.24% of the population’s living security and 10.36% of the socio-economic aggregate. The siphon effect of urbanization will increase the scale of regional agriculture and livestock development in the non-core urban areas of the BTH region, further increasing the demand for water

Sustainability 2019, 11, 3693; doi:10.3390/su11133693 www.mdpi.com/journal/sustainability Sustainability 2019, 11, 3693 2 of 18 resources [10,11]. However, 65% of the surface rivers in the BTH region are facing a shortage of water resources due to seasonal flows, as well as water shortages because of agricultural non-point source pollution and secondary pollution from transferred ecological water [12,13]. Regional agriculture and livestock development has caused significant stress on the ecological health of river water and the sustainable use of water resources in the BTH region [14]. With regard to the scarcity of regional water resources, the governments in the BTH region have adopted water-saving control measures to deal with the impact of water shortages [15–17]. However, the control measures focus on cross-regional water resource regulation in the core urban areas, or small-scale agricultural water-saving demonstrations and experiments in the non-core urban areas; no effective measures have been taken to restrict the over-exploitation of water resources in regional agriculture and livestock production [18,19]. Given the current climatic conditions, which are relatively stable, it will be difficult to change the trend of regional water shortages in the short to medium term [20]. It is, therefore, necessary to maintain a dynamic balance between the development of agriculture and livestock production and the conservation and recovery of water resources [21]. The water footprint theory was proposed in 2002. Because of its simple and easy application, this theory has been extensively used in research into the consumption and evaluation of water resources at macro scales, such as national and regional levels [22–27]. Researchers have explored the impacts of land use, typical crop production, pollution risk, demographic change, and socioeconomic fluctuations on regional water resources at province and city levels in the BTH region [15,18,28–31]. However, existing studies rarely involved small-scale horizontal comparisons between counties, which weakens the analysis of spatial differences in the water footprint and affects the feasibility of implementing recommendations. Temporally, previous studies have not analyzed the long-term cumulative effects of changes in the water footprint, and have ignored the analysis of regional water resources under different precipitation conditions. Regional evaluation studies also reduce the effect of natural differences in the distribution of agriculture and livestock development caused by factors such as terrain and urbanization. In the present study, we estimated the water footprint of agriculture and livestock (WF-AL) in 155 counties (including districts) in the non-core urban areas of the BTH region from 2000 to 2016 based on typical agriculture and livestock production. We then analyzed the distribution of the WF-AL based on precipitation and terrain characteristics across different areas. The main objectives of this study were: (1) to quantitatively evaluate the spatiotemporal variation of the WF-AL in the BTH region in 2000–2016; (2) to estimate the response pressure of agricultural and livestock development on water resources in the BTH region across different levels of annual precipitation; and (3) to provide recommendations and plans for adjusting the distribution of agriculture and livestock industries and improving the allocation of water resources. The results can help to optimize water resource allocation and implement a sustainable medium and long-term development plan for agriculture and livestock in the BTH region. The study also provides a reference for research into the conservation of water resources in similar semi-arid and semi-humid areas.

2. Materials and Methods

2.1. Study Region The BTH region is located in the Haihe River Basin in northern China. This region is comprised of the Beijing municipality, Tianjin municipality, and Hebei Province, with a total area of approximately 216,000 km2. The terrain is complex, generally tilting from the northwest to the southeast, consisting of a mountain area, a buﬀer zone (mountain–plain transition zone), a plains area, and a coastal plain (Figure1). The BTH region has a temperate continental monsoon climate. The average annual precipitation range is between 400 and 600 mm from north to south and the precipitation is mostly concentrated in June–September, which is typical for a semi-arid and semi-humid area. The BTH region covers 13 cities, from which the speciﬁc areas studied here were selected according to the “Beijing-Tianjin-Hebei Collaborative Development Plan” and the “13th Five-Year Development Sustainability 2019, 11, 3693 3 of 18

Plan” of each city, as well as the development trends of counties and their diﬀerences in industrial and agricultural development (as of 2018). After excluding the core urban areas of each city, a total of 155 county-level administrative areas were selected to form the study region for WF-AL in the BTH region. These included 31 counties in the mountain area, 37 counties in the buﬀer zone, 80 counties in the plainsSustainability area, 2019 and, 11 7, x counties FOR PEER onREVIEW the coastal plain. 3 of 19

(a) study area (b) terrain types

Figure 1. Study area and terrain types. 94 Figure 1. Study area and terrain types. Yield data for major agricultural and livestock products and area data for administrative divisions 95 The BTH region covers 13 cities, from which the specific areas studied here were selected 96in theaccording 155 county-level to the “Beijing administrative-Tianjin-Hebei areasCollaborative from 2000 Development to 2016 werePlan” derivedand the “13th from Five the-Year relevant 97statistical Development yearbooks Plan” and of socioeconomic each city, as well statistical as the development bulletins oftrends Beijing, of counties Tianjin, and and their Hebei differences (2000–2017) 98(http: in//www.nlc.cn industrial and/). agricultural The data on development precipitation (as and of 2018). water After resource excluding use were the core derived urban from areas province of each /city 99water city, resource a total bulletinsof 155 county and-level city administrative statistical yearbooks areas were (2000–2017). selected to form Classification the study region of the for terrain WF- and 100watersheds AL in the was BTH based regio onn. theThese 30-m included digital 31 elevation counties modelin the mountain of China area, (2010). 37 counties in the buffer 101 zone, 80 counties in the plains area, and 7 counties on the coastal plain. 1022.2. WF-ALYield Analysis data for major agricultural and livestock products and area data for administrative 103 divisions in the 155 county-level administrative areas from 2000 to 2016 were derived from the 1042.2.1. relevant Calculation statistical Methods yearbooks and socioeconomic statistical bulletins of Beijing, Tianjin, and Hebei 105 (2000–2017) (http://www.nlc.cn/). The data on precipitation and water resource use were derived The water footprint refers to the sum of water resources contained in direct or indirect goods and 106 from province/city water resource bulletins and city statistical yearbooks (2000–2017). Classification 107services of the consumed terrain and by watershed humans pers was year based within on the a certain 30-m digital area [elevation32]. Agriculture model of and China livestock (2010). production and subsequent product consumption are an integral part of human production and livelihoods, as 108well as2.2. one WF of-AL the Analysis most important forms of water consumption [33]. The water footprint of agriculture and livestock (WF-AL) refers to the total water consumption during the life cycle of agricultural 109production 2.2.1. Calculati and livestockon Methods breeding, in which the life cycle of agricultural and livestock products is 110generally The one water year footprint [34]. Currently, refers to therethe sum are of two water main resources methods contained for the in calculationdirect or indirect of WF-AL: goods the 111top-down and services evaluation consumed method by andhumans the provinceper year /withincity-level a certain bottom-up area [32 accumulation]. Agriculture methodand livestock [35,36 ]. 112 Aproduction third method, and subsequent the county-level product consumption bottom-up accumulationare an integral method,part of human is based production on county-level and 113sub-units, livelihoods while, as the well data as are one dependent of the most on important county statistical forms ofyearbooks. water consumption The county-level [33]. The methodwater is 114 footprint of agriculture and livestock (WF-AL) refers to the total water consumption during the life superior to the two methods mentioned above in terms of its use for the quantification, evaluation, 115 cycle of agricultural production and livestock breeding, in which the life cycle of agricultural and and optimal management of small and medium-sized watershed units across administrative areas. 116 livestock products is generally one year [34]. Currently, there are two main methods for the 117Therefore, calculation the county-level of WF-AL: bottom-upthe top-down accumulation evaluation method method and was the adopted province/city to calculate-level WF-ALbottom-up and its 118spatial accumulation density in ourmethod study [35 region.,36]. The calculation methods are expressed as follows: 119 A third method, the county-level bottom-up accumulationX method, is based on county-level sub- 120 units, while the data are dependentWF on countyAL = statisticalPi VW yearbooks. The county-level method is (1) − × 121 superior to the two methods mentioned above in terms of its use for the quantification, evaluation, 122where and WF-AL optimal represents management the of total small WF-AL and medium in a region,-sized watershed which quantifies units across the administrative water consumption areas. of 123regional Therefore, agriculture the county and-level livestock; bottom P-iuprepresents accumulation the method mass of was an adopted agriculture to calculate and livestock WF-AL and product 124 its spatial density in our study region. The calculation methods are expressed as follows: Sustainability 2019, 11, 3693 4 of 18 consumed in the corresponding region; and VW represents the virtual water content per unit mass of the agricultural and livestock products in the corresponding region.

WF AL ρ[WF AL] = − (2) − ρ Area H2O × where ρ[WF-AL] represents the spatial density of WF-AL in a region, which measures the spatial variation 3 of WF-AL per unit area in the region; ρH2O represents the density of water (ρH2O = 1000 kg/m ); and Area represents the area corresponding to the region.

WF AL L[WF AL] = ρ[WF AL] P = − P (3) − − − ρ Area − H2O × where L[WF-AL] represents the diﬀerence between the spatial density of WF-AL and the annual precipitation in a region, which measures the development intensity and surplus or loss of water resources for agriculture and livestock in the region and P refers to the annual precipitation in the region. L[WF-AL] < -200mm indicates that the development of regional water resources is in a healthy state, while L ( 100,100) mm indicates a relatively balanced state and L > 400mm [WF-AL] ∈ − [WF-AL] indicates an unstable state [37].

1 WF AL 1 K[WF AL] = ρ[WF AL] = − (4) − − × P ρ Area × P H2O × where K[WF-AL] represents the ratio between the spatial density of the WF-AL and the annual precipitation in a region, which measures the response relationship between regional agriculture and livestock development and precipitation.

2.2.2. Virtual Water Content of Agriculture and Livestock Products The WF-AL per unit mass is numerically equivalent to its virtual water content, which is determined by water consumption during the production process of crop planting/livestock rearing. In the non-urban industrial areas, agriculture and livestock products form the most important part of regional water consumption. There are two main methods for calculating the virtual water content of agricultural products (VWc): estimation based on the measured evapotranspiration of crops, and estimation based on the inversion of products. For estimation of a long-term series of virtual water content for agriculture and livestock, the former method is applied to single small watersheds with station observation experiments, while the latter method is applied to watersheds with limited empirical data and a large area. Limited to the measured meteorological data in the BTH region, the actual evapotranspiration of agricultural products is difficult to obtain. Here, we adopted the inversion of products method to estimate the VWc of agricultural products. We selected agricultural products with a total yield > 5% throughout the study region. These products included eight food crops and cash crops. Their VWc values are listed in Table1[ 38–41]. The virtual water content of livestock products (VWa) refers to the water consumption in the life cycle of livestock production during feeding. Because large-scale farming is the dominant method for the main livestock products in the study region, we selected six typical livestock products based on the results of similar studies in this region. Their VWa values are given in Table1[14,32,42–48].

Table 1. Virtual water consumption of agriculture and livestock products in the Beijing–Tianjin–Hebei (BTH) region (m3/kg).

Agricultural and Livestock Products Region Grain Crops Cash Crops Livestock Products Wheat Maize Paddy Tubers Peanut Cotton Vegetable Fruit Pork Beef Mutton Poultry Egg Milk Hebei 1.38 1.19 2.19 1.2 1.2 5.5 0.1 0.68 Beijing 1.23 0.84 1.4 0.7 1.5 4.4 0.2 0.58 3.6 18.1 19.98 3.50 8.65 2.2 Tianjin 1.25 0.76 1.19 0.88 1.5 5.22 0.1 0.48 Sustainability 2019, 11, 3693 5 of 18 Sustainability 2019, 11, x FOR PEER REVIEW 6 of 19

3. Results 3. Results 3.1. Structure of the WF-AL 3.1. Structure of the WF-AL 3.1.1. County WF-AL

3.1.1. County WF-AL 8 3 From 2000 to 2016, the average annual county WF-AL (WF-ALcounty) increased from 8.03 10 m 8 3 × 8 3 to 10.89From10 2000m .to The 2016, average the average annual annual growth county rate of WF-AL WF-AL (WF-ALcounty wascounty 1.9%,) increased indicating from 8.03 a slow × 10 upward m × 8 3 trend.to 10.89 However, × 10 m for. The individual average annual counties, growth there rate were of WF-AL spatiotemporalcounty was di1.9%,ﬀerences indicating in WF-AL a slowcounty upward. From 2000trend. to 2002,However, the Chonglifor individual District counties, of Zhangjiakou there were hadspatiotemporal the lowest differences value (0.39 in WF-AL108 mcounty3), while. From the × maximum2000 to 2002, value the was Chongli found Districtin the Gaogcheng of Zhangjiakou District had of the Shijiazhuang lowest value (31.69 (0.39 ×10 108 m8 m3).3), In while 2015–2016, the × 8 3 themaximum Mentougou value District was found of Beijing in the hadGaogcheng the lowest District value of Shijiazhuang (0.25 108 m (31.693), while × 10 them ). maximum In 2015–2016, value × 8 3 occurredthe Mentougou in the Xinji District County of ofBeijing Shijiazhuang had the (34.65lowest value108 m (0.253; Figure × 102).m The), while average the annualmaximum growth value rate occurred in the Xinji County of Shijiazhuang (34.65× × 108 m3; Figure 2). The average annual growth of the Max(WF-ALcounty) was 0.6%, while the Min(WF-ALcounty) had an average annual growth rate of rate of the Max(WF-ALcounty) was 0.6%, while the Min(WF-ALcounty) had an average annual growth 4.9%. The ratio of Max(WF-ALcounty) to Min(WF-ALcounty) increased from 81.3 in the early stage to 138.6 rate of 4.9%. The ratio of Max(WF-ALcounty) to Min(WF-ALcounty) increased from 81.3 in the early stage in the later stage. In regard to spatial distribution, the top 10% of areas in terms of Max(WF-ALcounty) to 138.6 in the later stage. In regard to spatial distribution, the top 10% of areas in terms of Max(WF- showed an agglomeration eﬀect. Most were located in the plain areas of Shijiazhuang and Handan, or ALcounty) showed an agglomeration effect. Most were located in the plain areas of Shijiazhuang and the coastal plain of Tangshan. By contrast, the top 10% of areas in terms of Min(WF-AL ) were Handan, or the coastal plain of Tangshan. By contrast, the top 10% of areas in terms of countyMin(WF- scattered in the northwest and central east of the BTH region. ALcounty) were scattered in the northwest and central east of the BTH region.

(a) 2000–2002 (b) 2003–2005

Figure 2. Cont.

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(e) 2012–2014 (f) 2015–2016

Figure 2. County water footprint of agriculture and livestock production (WF-ALcounty) of the BTH 17 region,Figure 2000–2016. 2. County water footprint of agriculture and livestock production (WF-ALcounty) of the BTH 18 region, 2000–2016.

Based on Figure2, we selected 30% and 70% of the average WF-AL county as the reference values [49]. 19 Based on Figure 2, we selected 30%8 and3 70% of the average8 3 WF-ALcounty as the reference values Thus, the WF-ALcounty values 7.13 10 m and 11.26 10 m were used as the thresholds for regional 20 [49]. Thus, the WF-ALcounty values× 7.13 × 108 m3 and ×11.26 × 108 m3 were used as the thresholds for low–medium, and medium–high water consumption in the BTH region. Table2 shows that the 21 regional low–medium, and medium–high water consumption in the BTH region. Table 2 shows that proportion of counties with low water consumption gradually decreased from 51.6% to 32.9%, while 22 the proportion of counties with low water consumption gradually decreased from 51.6% to 32.9%, the proportion of counties with high water consumption doubled from 19.4% to 38.1%. The proportion 23 while the proportion of counties with high water consumption doubled from 19.4% to 38.1%. The of counties with medium water consumption showed periodic fluctuations, but generally remained 24 proportion of counties with medium water consumption showed periodic fluctuations, but generally 25 unchanged.remained unchanged. Spatially, the Spatially, low water the consumption low water consumption areas which areas were which located were in the located mountain in the area 26 andmountain buffer zonearea and became buffer medium zone became water medium consumption water consumption areas, while theareas, medium while the water medium consumption water 27 areasconsumption located in areas the bulocatedffer zone in the and buffer plains zone area and becameplains area high became water high consumption water consumption areas. The areas. water 28 consumptionThe water consumption in the BTH region in the progressively BTH region increased progressively from increased the northwest from to the the northwest southeast. to the 29 southeast. Table 2. Proportional distribution of the county water footprint of agriculture and livestock 30 (WF-ALTable county 2. Proportional) in the Beijing–Tianjin–Hebei distribution of the county (BTH) water region, footprint 2000–2016. of agriculture and livestock (WF- 31 ALcounty) in the Beijing–Tianjin–Hebei (BTH) region, 2000–2016. 2000–2002 2003–2005 2006–2008 2009–2011 2012–2014 2015–2016 Low consumption 2000–200251.6% 2003–2005 44.5% 2006–2008 43.2% 2009–2011 36.8% 2012–2014 30.3% 2015–2016 32.9% Medium consumption 29.0% 27.1% 32.9% 28.4% 34.2% 29.0% Low consumption 51.6% 44.5% 43.2% 36.8% 30.3% 32.9% High consumption 19.4% 28.4% 23.9% 34.8% 35.5% 38.1% Medium consumption 29.0% 27.1% 32.9% 28.4% 34.2% 29.0% 3.1.2.High City consumption WF-AL 19.4% 28.4% 23.9% 34.8% 35.5% 38.1%

32 3.1.2.The City average WF-AL city WF-AL (WF-ALcity) of Tangshan, Shijiazhuang, Handan, and Qinhuangdao was higher than 11.26 108 m3, which is in the high water consumption category (Figure3). By contrast, 33 The average× city WF-AL (WF-ALcity) of Tangshan, Shijiazhuang, Handan,8 3 and Qinhuangdao was the average WF-ALcity of Zhangjiakou was lower than 7.13 10 m , which is in the low water 34 8 3 × consumptionhigher than 11.26 category. × 10 Them , which remaining is in the eight high cities water were consumption in the medium category water (Figure consumption 3). By contrast, category, 35 the average WF-ALcity of Zhangjiakou was lower than 7.13 × 108 m3, which is in the low water although Hengshui and Cangzhou were close to the high water consumption category (i.e., WF-ALcity 36 consumption category. The remaining eight cities were in the medium water consumption category, was generally within the range of medium–high water consumption). From 2000 to 2016, the average 37 although Hengshui and Cangzhou8 were3 close to the high8 3 water consumption category (i.e., WF-ALcity WF-ALcity increased from 8.00 10 m to 11.05 10 m , with an average annual growth rate of 2.0%. 38 was generally within the range× of medium–high× water consumption). From 2000 to8 2016,3 the average8 3 The average annual WF-ALcity of the 13 cities ﬂuctuated in the range of 2.92 10 m –18.99 10 m . 39 WF-ALcity increased from 8.00 × 108 m3 to 11.05 × 108 m3, with an average annual× growth rate of× 2.0%. 40 The average annual WF-ALcity of the 13 cities fluctuated in the range of 2.92 × 108 m3–18.99 × 108 m3.

Sustainability 2019, 11, 3693 7 of 18 Sustainability 2019, 11, x FOR PEER REVIEW 8 of 19 Sustainability 2019, 11, x FOR PEER REVIEW 8 of 19

600 600 ） 3

） 18.00 3 m 18.00 8 m 8 500 500 14.00 14.00 400 10.00 400 10.00

300 (Average County,10 (Average 6.00 300

(Average County,10 (Average 6.00 Average (mm) Average Precipitation city Average (mm) Average Precipitation city

WF 2.00 200

2000-2002 2003-2005 2006-2008 2009-2011 2000-2002 2003-2005 2006-2008 2009-2011 2012-2014 2015-2016 2000-2016 2012-2014 2015-2016 2000-2016

Figure 3.3. CityCity waterwater footprintfootprint ofof agricultureagriculture andand livestocklivestock (WF-AL(WF-ALcitycity) inin thethe Beijing–Tianjin–HebeiBeijing–Tianjin–Hebei Figure 3. City water footprint of agriculture and livestock (WF-ALcity) in the Beijing–Tianjin–Hebei (BTH)(BTH) region,region, 2000–2016.2000–2016. (BTH) region, 2000–2016. After subdividingsubdividing the the water water consumption consumption of eachof each city intocity counties,into counties, we found we thatfound the that WF-AL thecounty WF- showedAfter fluctuations subdividing consistent the water with consumption the corresponding of each city WF-AL into counties,in Tangshan, we found Hengshui, that the WF- and ALcounty showed fluctuations consistent with the corresponding WF-ALcity city in Tangshan, Hengshui, CangzhouALcounty showed (Figure fluctuations4). However, consistent there was with an the increase corresponding of WF-AL WF-ALcounty cityin localin Tangshan, areas or Hengshui, an overall and Cangzhou (Figure 4). However, there was an increase of WF-ALcounty in local areas or an overall decreasingand Cangzhou trend (Figure of WF-AL 4). However,found there in Zhangjiakou, was an increase Baoding, of WF-AL Shijiazhuang,county in local and areas Handan. or an overall Most decreasing trend of WF-ALcitycity found in Zhangjiakou, Baoding, Shijiazhuang, and Handan. Most decreasing trend of WF-ALcity found in Zhangjiakou, Baoding, Shijiazhuang, and Handan. Most counties in these four cities were located in the mountain area area and buffer buffer zone of the BTH region. Thiscounties demonstrates in these four that cities the spatial were dilocatedfferences in the in themountain WF-AL areawere and substantiallybuffer zone of reduced the BTH compared region. This demonstrates that the spatial differences in the WF-ALcitycity were substantially reduced compared withThis demonstrates those in the WF-AL that thecounty spatial. differences in the WF-ALcity were substantially reduced compared with those in the WF-ALcounty. with those in the WF-ALcounty.

100% 100%

80% 80%

60% 60%

40% 40%

20%

Ratio of Consumptionof Ratio Water 20% Ratio of Consumptionof Ratio Water 0% 0%

Low consumption Medium consumption High consumption Low consumption Medium consumption High consumption

Figure 4. Spatial didifferencesfferences withinwithin thethe citycity waterwater footprintfootprint ofof agricultureagriculture andand livestocklivestock (WF-AL (WF-ALcity)) inin Figure 4. Spatial differences within the city water footprint of agriculture and livestock (WF-ALcitycity) in thethe Beijing–Tianjin–HebeiBeijing–Tianjin–Hebei (BTH)(BTH) region.region. the Beijing–Tianjin–Hebei (BTH) region. 3.1.3. Terrain WF-AL 3.1.3. Terrain WF-AL Because the the development development of agriculture of agriculture and livestock and livestock varies with varies terrain, with there terrain, were considerable there were Because the development of agriculture and livestock varies with terrain, there were diconsiderablefferences in differences the planting in structure the planting of crops structure and the of typecrops of and livestock. the type The of BTHlivestock. region The can BTH be divided region considerable differences in the planting structure of crops and the type of livestock. The BTH region intocan be a mountain divided into area, a mountain a buffer zone, area, a a plains buffer area, zone, and a plains a coastal area, plain and (Figurea coastal1). plain The terrain(Figure WF-AL 1). The can be divided into a mountain area, a buffer zone, a plains area, and a coastal plain (Figure 1). The (WF-ALterrain terrain WF-AL) of (WF-AL the bufferterrain zone) of was thegenerally buffer zone close was to WF-AL generallycounty close, while to the WF-AL correspondingcounty, while values the terrain WF-AL (WF-ALterrain) of the buffer zone was generally close to WF-ALcounty, while the corresponding values of the mountain area and the plains area respectively decreased by 21.9% and corresponding values of the mountain area and the plains area respectively decreased by 21.9% and 7.2%, and the value of the coastal plain markedly increased by 22.4% (Table 3). 7.2%, and the value of the coastal plain markedly increased by 22.4% (Table 3).

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Sustainability 2019, 11, x FOR PEER REVIEW 9 of 19 of the mountain area and the plains area respectively decreased by 21.9% and 7.2%, and the value of the coastalTable 3. plain Distribution markedly of increasedthe terrain bywater 22.4% footprint (Table of3 ).agriculture and livestock (WF-ALterrain) in the Beijing–Tianjin–Hebei (BTH) region, 2000–2016 (108 m3). Table 3. Distribution of the terrain water footprint of agriculture and livestock (WF-ALterrain) in the Beijing–Tianjin–Hebei2000– (BTH)2003– region, 2000–20162006– (1082009–m3). 2012– 2015– County Number 2002 2005 2008 2011 2014 2016 County 2000–2002 2003–2005 2006–2008 2009–2011 2012–2014 2015–2016 Mountain Area 3.79 4.90 5.44 6.01 6.82 7.53 Number 31 BufferMountain Zone Area 8.63 3.79 9.53 4.90 9.33 5.44 10.28 6.01 10.95 6.82 10.89 7.53 31 37 Buﬀer Zone 8.63 9.53 9.33 10.28 10.95 10.89 37 Plain AreaPlain Area 9.36 9.36 10.62 10.62 10.44 10.44 11.36 11.36 11.89 11.89 11.91 11.91 80 80 Coastal Plain 8.21 9.81 10.25 12.64 13.67 13.80 7 Coastal Plain 8.21 9.81 10.25 12.64 13.67 13.80 7

Under similarsimilar climaticclimatic conditions, conditions, the the land land area area of of agricultural agricultural planting planting in thein the mountain mountain area area and andthe butheffer buffer zone zone was smaller was smaller than that than in that the plainin the area plain and area the and coastal the plaincoastal due plain to limitations due to limitations imposed imposedby the terrain. by the Interrain. contrast, In contrast, livestock livestock farming farming was developed was developed on a larger on a larger scale inscale the in mountain the mountain area areaand buandffer buffer zone zone compared compared with thewith other the other two terrains. two terrains. Thus, Thus, there werethere importantwere important differences differences in the indevelopment the development pattern pattern of agriculture of agriculture and livestock and livestock production production between between these terrains, these terrains, and their and WF-AL their WF-ALratios were ratios not were comparable. not comparable. The WF-AL The ratiosWF-AL of agricultureratios of agriculture and livestock and productslivestock inproducts the mountain in the mountainarea and plain area area and were plain much area higher were muchthan those higher in the than bu thoseffer zone in andthe buffer coastal zone plain and (Figure coastal5). This plain is (Figurebecause, 5). compared This is because, to agricultural compared products, to agricultural livestock productsproducts, require livestock secondary products processing require secondary with more processingcomplex processes with more of watercomplex consumption. processes of The water climatic consumption. conditions The of climatic the semi-arid conditions and semi-humidof the semi- aridregions and make semi-humid them unsuitable regions make for large-scale them unsuitable farming for of livestocklarge-scale because farming of limitedof livestock water because resources. of limited water resources.

130.0%

110.0%

90.0%

livestock productslivestock 70.0%

Water footprint ratios of of andWater agricultureratios footprint 50.0% 2000-2002 2003-2005 2006-2008 2009-2011 2012-2014 2015-2016

Mountain Area Buffer Zone

Plain Area Coastal Plain

Figure 5. Water footprint ratios of agriculture and livestock products in the Beijing–Tianjin–Hebei (BTH) region. 3.2. Density Variation of the WF-AL 3.2. Density Variation of the WF-AL 3.2.1. Surplus or Loss of Water Footprint Density 3.2.1. Surplus or Loss of Water Footprint Density In the northwest and southeast areas of the BTH region (Figure6), the L [WF-AL] overall remained < 0 fromIn the 2000 northwest to 2008, indicatingand southeast a healthy areas andof the balanced BTH region state of(Figure regional 6), waterthe L[WF-AL] resource overall development. remained < 0 from 2000 to 2008, indicating a healthy and balanced state of regional water resource development. However, a fragmented and patchy trend was found in these areas from 2009 to 2016, with L[WF-AL] >However,400 mm a in fragmented some counties and (e.g.,patchy Zhuolu trend andwas Huailaifound in of these Zhangjiakou). areas from This2009 indicatesto 2016, with that L regional[WF-AL] > water400 mm resource in some development counties (e.g., shifted Zhuolu into and an unstable Huailai state.of Zhangjiakou). In the west andThis central indicates areas that of theregional BTH water resource development shifted into an unstable state. In the west and central areas of the BTH region, the L[WF-AL] gradually increased from 2000, with periodic ﬂuctuations in local areas. There wasregion, no the obvious L[WF-AL] center gradually of surplus increased or loss from for 2000, regional with waterperiodic resources, fluctuations and in regional local areas. water There resource was nodevelopment obvious center varied of between surplus stable or loss and for unstable regional states. water resources, and regional water resource development varied between stable and unstable states. Long-term significant losses of water resources were found in the north, central southwest, and central east areas of the BTH region. The L[WF-AL] was between 100 and 200 mm in local areas only before 2008, while it was > 400 mm in the remaining areas with the Max[L[WF-AL]] close to 2000 mm.

Sustainability 2019, 11, x FOR PEER REVIEW 10 of 19

Four areas with water resources in an unstable state were formed between 2015 and 2016, which respectively were centered in Xinji County, Shijiazhuang (L[WF-AL] = 1981 mm) and Daming County, HandanSustainability (L[WF-AL]2019, 11 =, 36931145 mm) in the plain area, Luannan County, Tangshan in the coastal plain (L9 of[WF- 18 AL] = 1847 mm), and Weichang County, Chengde in the mountain area (L[WF-AL] = 618 mm).

(a) 2000–2002 (b) 2003–2005

(e) 2012–2014 (f) 2015–2016

Figure 6. Diﬀerences in the water footprint density of agriculture and livestock (L[WF-AL]) in the Beijing–Tianjin–Hebei (BTH) region, 2000–2016. Sustainability 2019, 11, x FOR PEER REVIEW 11 of 19

Figure 6. Differences in the water footprint density of agriculture and livestock (L[WF-AL]) in the Beijing– Tianjin–Hebei (BTH) region, 2000–2016.

SustainabilityBetween2019 2000, 11, 3693 and 2016, L[WF-AL] showed small fluctuations within the six intervals between10 –200 of 18 mm and 400 mm, while negatively correlated fluctuations were found within the two intervals of L[WF-AL] < –200 mm and > 400 mm (Table 4). The healthy development areas of water resources sharply Long-term signiﬁcant losses of water resources were found in the north, central southwest, and decreased during 2000–2014, whereas the unstable development areas rapidly increased in 2003–2005 central east areas of the BTH region. The L[WF-AL] was between 100 and 200 mm in local areas only and 2009–2014. The L[WF-AL] was relatively stable between 2015 and 2016. before 2008, while it was > 400 mm in the remaining areas with the Max[L[WF-AL]] close to 2000 mm.

FourTable areas 4. with Proportional water resources distribution in of an the unstable water footprint state weredensity formed of agriculture between and 2015 livestock and (L 2016,[WF-AL] which) respectivelyin the Beijing–Tianjin–Hebei were centered in Xinji (BTH) County, region, 2000–2016. Shijiazhuang (L[WF-AL] = 1981 mm) and Daming County, Handan (L[WF-AL] = 1145 mm) in the plain area, Luannan County, Tangshan in the coastal plain (L = 1847 mm), and(−200,−100 Weichang County, Chengde in the mountain area (L = 618 mm). L[WF-AL][WF-AL] (mm) <−200 (−100,0) (0,100) (100,200) （200,300） [WF-AL]（300,400） >400 Between 2000 and 2016,) L[WF-AL] showed small ﬂuctuations within the six intervals between –2002000–2002 mm and 40027.7% mm, while9.7% negatively 14.2% correlated 14.8% ﬂuctuations 9.7% were found4.5% within4.5% the two intervals14.8% of L < –200 mm and > 400 mm (Table4). The healthy development areas of water resources 2003–2005[WF-AL] 23.9% 11.0% 8.4% 11.6% 10.3% 9.7% 4.5% 20.6% sharply decreased during 2000–2014, whereas the unstable development areas rapidly increased in 2006–2008 21.3% 10.3% 12.3% 13.5% 8.4% 8.4% 7.1% 18.7% 2003–2005 and 2009–2014. The L[WF-AL] was relatively stable between 2015 and 2016. 2009–2011 16.1% 11.6% 10.3% 12.3% 10.3% 6.5% 7.7% 25.2%

2012–2014Table 4. Proportional9.0% distribution14.8% of10.3% the water footprint12.3% density10.3% of agriculture9.0% and livestock5.2%(L [WF-AL]29.0%) in the Beijing–Tianjin–Hebei (BTH) region, 2000–2016. 2015–2016 9.7% 12.3% 10.3% 16.1% 9.0% 6.5% 5.2% 31.0% L (mm) < 200 ( 200, 100) ( 100,0) (0,100) (100,200) (200,300) (300,400) >400 [WF-AL] − − − − 3.2.2.2000–2002 Ratio of Water 27.7% Footprint Density 9.7% 14.2% 14.8% 9.7% 4.5% 4.5% 14.8% 2003–2005 23.9% 11.0% 8.4% 11.6% 10.3% 9.7% 4.5% 20.6% 2006–2008Owing to the 21.3%huge terrain 10.3% differences, 12.3% microclimate 13.5% variations 8.4% are found 8.4% in local 7.1% areas 18.7% of the BTH 2009–2011region, and the 16.1% precipitation 11.6% fluctuates 10.3% substantially 12.3% at the 10.3%county level. 6.5% Therefore, 7.7% we used 25.2% the 2012–2014 9.0% 14.8% 10.3% 12.3% 10.3% 9.0% 5.2% 29.0% ratio 2015–2016of water footprint 9.7% density 12.3% to reduce 10.3%the spatial 16.1%differences 9.0% across the 6.5% region and 5.2% quantify 31.0% the level of regional water resource development and use over time and space (Figure 7). 3.2.2.The Ratio proportion of Water of Footprint counties Density with K[WF-AL] < 40% decreased from 12.3% in 2000 to 5.8% in 2008, and then remained almost constant until 2016 (Table 5). The proportion of counties with K[WF-AL] in the rangeOwing of 40%–70% to thehuge decreased terrain from differences, 22.6% in microclimate 2008 to 9.0% variations in 2016. are No found significant in local fluctuations areas of the were BTH region, and the precipitation fluctuates substantially at the county level. Therefore, we used the ratio found in the proportion of counties with K[WF-AL] in the range of 70%–90% or 90%–110%. However, of water footprint density to reduce the spatial differences across the region and quantify the level of the proportion of counties with K[WF-AL] > 110% significantly increased from 41.3% in 2000 to 60.6% in 2016,regional and water the increase resource mostly development occurred and in the use range over timeof >200%. and space (Figure7).

(a) 2000–2002 (b) 2003–2005

Figure 7. Cont.

SustainabilitySustainability 20192019,, 1111,, x 3693 FOR PEER REVIEW 1211 of of 19 18

(e) 2012–014 (f) 2015–2016

Figure 7. Water footprint density ratio of agriculture and livestock (K[WF-AL]) in the FigureBeijing–Tianjin–Hebei 7. Water footprint (BTH) density region, ratio 2000–2016. of agriculture and livestock (K[WF-AL]) in the Beijing–Tianjin– Hebei (BTH) region, 2000–2016. The proportion of counties with K[WF-AL] < 40% decreased from 12.3% in 2000 to 5.8% in 2008, andTable then remained 5. Proportional almost distribution constant untilof the 2016 water (Table footprint5). The density proportion ratio of ofagriculture counties and with livestock K [WF-AL] in the range(K[WF-AL] of) 40%–70%in the Beijing–Tianjin–Hebei decreased from 22.6%(BTH) inregion, 2008 2000–2016. to 9.0% in 2016. No significant fluctuations were found in the proportion of counties with K[WF-AL] in the range of 70%–90% or 90%–110%. However, K[WF-AL] <40% 40%–70% 70%–90% 90%–110% >110% >200% the proportion of counties with K[WF-AL] > 110% significantly increased from 41.3% in 2000 to 60.6% in 2016,2000–2002 and the increase 12.3% mostly occurred 21.3% in the range 10.3% of >200%. 14.8% 41.3% 12.9% 2003–2005 7.1% 21.3% 8.4% 12.9% 50.3% 16.8% 2006–2008Table 5. Proportional 5.8% distribution 22.6% of the water 9.7% footprint density 15.5% ratio of agriculture 46.5% and livestock 17.4% (K ) in the Beijing–Tianjin–Hebei (BTH) region, 2000–2016. 2009–2011[WF-AL] 5.8% 12.9% 12.9% 11.6% 56.8% 19.4%

2012–2014K[WF-AL] 5.2%<40% 11.0% 40%–70% 70%–90% 12.9% 90%–110% 11.6% >110% 59.4% >200% 23.9% 2015–20162000–2002 5.8% 12.3% 9.0% 21.3% 11.0% 10.3% 14.8%13.5% 41.3% 60.6% 12.9% 25.8% 2003–2005 7.1% 21.3% 8.4% 12.9% 50.3% 16.8% 2006–2008Taking the development 5.8% and use 22.6% rate of river 9.7% water resources 15.5% at 40% as the 46.5% standard 17.4%threshold for classifying2009–2011 the carrying 5.8% capacity 12.9% of river development, 12.9% only11.6% 5.8% of counties 56.8% in the BTH 19.4% region 2012–2014 5.2% 11.0% 12.9% 11.6% 59.4% 23.9% consistently met this standard [50,51]. Most of these areas were distributed in the mountain area 2015–2016 5.8% 9.0% 11.0% 13.5% 60.6% 25.8% (Shangyi County of Zhangjiakou, and Laiyuan and Fuping County of Baoding) and the buffer zone (Mentougou and Changping District of Beijing). This is because the counties of Shangyi, Laiyuan,

Sustainability 2019, 11, 3693 12 of 18

Taking the development and use rate of river water resources at 40% as the standard threshold for classifying the carrying capacity of river development, only 5.8% of counties in the BTH region consistently met this standard [50,51]. Most of these areas were distributed in the mountain area (Shangyi County of Zhangjiakou, and Laiyuan and Fuping County of Baoding) and the buffer zone (Mentougou and Changping District of Beijing). This is because the counties of Shangyi, Laiyuan, and Fuping have natural groundwater supplies, with nearly 80% forest and grass coverage, complete surface river systems, and stable wetland, lake, and reservoir ecosystems. By contrast, in the Mentougou and Changping Districts, due to the policy restrictions of Beijing, the development of livestock is under strict control, and the areas suitable for agriculture have been used for urban development, which compensates for the limitations of an insufficient surface water supply and leads to a relatively low development and use rate of water resources. The plain area is concentrated in the Jinnan, Xiqing, and Dongli Districts of Tianjin. These three districts have a higher urbanization rate, with limited areas suitable for agricultural development and production. The livestock production in these counties is mainly based on fisheries, which has little impact on water consumption. In addition, these three counties are close to the estuary of Bohai Bay and receive high precipitation. The recent water supply by the Middle Line Project of South-to-North Water Division also contributes to abundant regional water resources in these counties.

3.3. Prediction and Early-Warning of WF-AL

3.3.1. Early-Warning in Different Precipitation Years We fitted the scenarios for four types of precipitation years (wet, relatively wet, relatively dry, and dry) with the development status of agriculture and livestock in the BTH region between 2015 and 2016 as the baseline (Figure8) [ 52]. The simulation was performed without consideration of future control measures such as the transformation of agriculture and livestock or the promotion of water-saving technologies. In the different precipitation years, the proportions of different terrains with K[WF-AL] < 0.4 were less than 15%. In particular, the proportions of the buffer zone and plains area were less than 5%. Thus, within the range of normal precipitation fluctuations, the development of agriculture and livestock approached or exceeded the threshold for the natural bearing capacity in most of the areas in the BTH region. However, with the K[WF-AL] of 0.4–0.7 and under the precipitation conditions of relatively wet and wet years, the proportions of the mountain area, buffer zone, plains area, and coastal plain that were stable were 19.4%, 10.8%–24.3%, 12.5%–15.0%, and 0.0%, respectively. This suggests that the water ecosystem health in the mountain area and buffer zone could recover in the short term if the precipitation conditions are suitable and the scale of agriculture and livestock is partially limited. The proportions of mountain area, buffer zone, and plains area with a of K[WF-AL] of 0.7–0.9 increased by 10.0%–13.5% during the conversion from dry years to wet years, while increase of the proportion of the coastal plain with this K[WF-AL] range reached 28.6%. For these areas, the variations in natural precipitation and the scale of agriculture and livestock development have comparable effects on the regional water ecosystems. Thus, the planning of sustainable production of agriculture and livestock should consider different precipitation conditions. In the wet years, the proportions of mountain area, buffer zone, plains area, and coastal plain with a K[WF-AL] > 0.9 reached 48.4%, 56.8%, 68.8%, and 57.1%, respectively. The mountain area was concentrated in Weichang County of Chengde and Zhuolu County of Zhangjiakou. The buffer zone counties included Luannan County of Tangshan, Dingzhou County of Baoding, and Wu’an County of Handan. The plains area was centered on Gaocheng County of Shijiazhuang and Daming County of Handan. The coastal plain was concentrated in Jinghai District of Tianjin and Changli County of Qinhuangdao. In the abovementioned areas, agriculture and livestock were over-developed, which had considerable negative effects on the enrichment of regional natural water resources. Therefore, while emphasizing the limited production of agriculture and livestock plus the protection of the Sustainability 2019, 11, 3693 13 of 18 region’s inherent interests, we should consider using the Middle Line Project of South-to-North Water

SustainabilityDivision as 2019 the, 11 main, x FOR trunk PEER to REVIEW build and connect the branch channels of cross-regional water transfer 14 of 19 in the BTH region, thereby constructing a high-speed water network in this water-deﬁcient region.

(a) wet year (b) relatively wet year

Figure 8. Water footprint density ratio of agriculture and livestock (K[WF-AL]) in the Beijing–Tianjin– FigureHebei (BTH)8. Water region footprint under density different ratio precipitation of agriculture years. and livestock (K[WF-AL]) in the Beijing–Tianjin– Hebei (BTH) region under different precipitation years. 3.3.2. Pressure Response Control of Water Resources 3.3.2. Cross-regionalPressure Response water Control transfer of Water channels Resources are similar to highway networks, and require comprehensiveCross-regional consideration water transfer of land resources channels and are construction similar to costs. highway Large, networks,medium, and and small-sized require comprehensivereservoir systems consideration are well-established of land resources in the mountainand construction area and costs. buff Large,er zone medium, of the BTH and region.small- sizedHowever, reservoir the overallsystems waterare well-established conservation functionin the mountain of natural area rivers, and buffer which zone are of the the links BTH between region. However,reservoirs, the is still overall weak water in these conservation areas. Only function some rivers of natural (Jumahe, rivers, Baihe, which and Luanhe) are the can links function between as reservoirs,water transfer is still channels. weak in Thethese geological areas. Only conditions some rivers are (Jumahe, complex, Baihe, and it and is di Luanhe)fficult to can construct function new as waterartificial transfer water channels. transfer channels The geological in a short conditions period of are time. complex, Therefore, and the it is adjustment difficult to plan construct for regional new artificialdevelopment water shouldtransfer be channels based on in limitinga short period the scale of time. of agricultural Therefore, the and adjustment livestock development plan for regional and developmentreservoir water should transfer. be based on limiting the scale of agricultural and livestock development and reservoirCompared water transfer. to the mountain area and buffer zone, it is obviously advantageous to construct a networkCompared of new to water the mountain transfer channelsarea and inbuffer the plainszone, it and is obviously coastal plain advantageous areas of the to BTHconstruct region. a networkIn addition of new to relying water ontransfer natural channels rivers, in the the construction plains and ofcoastal a new plain artificial areas water of the transfer BTH region. network In addition to relying on natural rivers, the construction of a new artificial water transfer network is feasible in terms of site selection, construction difficulty, and terrain and geological constraints. Especially in severely water-deficient areas, cross-regional water transfer should be combined with limited agriculture and livestock production to mitigate the regional water shortage.

Sustainability 2019, 11, x FOR PEER REVIEW 15 of 19

Therefore, taking into account the current situation of K[WF-AL] in different areas of the BTH region, we propose the following plan (Table 6, Figure 9) to establish the medium and long-term balance of agricultural and livestock development and water resource recovery. Sustainability 2019, 11, 3693 14 of 18 Table 6. The plan for limited production of agriculture and livestock in the Beijing–Tianjin–Hebei is feasible(BTH) in region. terms of site selection, construction diﬃculty, and terrain and geological constraints.

EspeciallyK[WF-AL], Now in severely K[WF-AL], water-deﬁcient Future areas, Limited cross-regional Limited water Production transfer shouldWater be combined Transfer with limited agriculture and livestock production to mitigate the regional water shortage. Production of of Livestock Therefore, taking into account the current situation of K[WF-AL] in diﬀerent areas of the BTH region, Agriculture we propose the following plan (Table6, Figure9) to establish the medium and long-term balance of agricultural0–0.4 and livestock Maintain development and water- resource recovery. - - 0.4–0.5 drop to 0.4 - 10% - Table 6. The plan for limited production of agriculture and livestock in the Beijing–Tianjin–Hebei 0.5–0.7 Drop to 0.4 10% 30% - (BTH) region. 0.7–0.8 Drop to 0.7 - 10% Reservoir water transfer Limited Production of Limited Production of K , Now K , Future Water Transfer [WF-AL]0.8–0.9 [WF-AL] Drop to 0.7 Agriculture 10% Livestock 10% Reservoir water transfer 0.9–1.10–0.4 Drop Maintain to 0.9 10% - 15% - Cross-region - water transfer 0.4–0.5 drop to 0.4 - 10% - 1.1–1.30.5–0.7 Drop toto 0.4 0.9 10% 30% 30% Cross-region - water transfer 0.7–0.8>1.3 Drop toto 0.7 0.9 30% - 30% 10% Cross-region Reservoir water water transfer transfer 0.8–0.9 Drop to 0.7 10% 10% Reservoir water transfer 0.9–1.1 Drop to 0.9 10% 15% Cross-region water transfer 1.1–1.3 Drop to 0.9 10% 30% Cross-region water transfer >1.3 Drop to 0.9 30% 30% Cross-region water transfer

Figure 9. Figure 9.A A schematicschematic for for limitedlimited production production of of agricultureagriculture and and livestock livestock in in the the Beijing–Tianjin–Hebei Beijing–Tianjin–Hebei (BTH)(BTH) region. region. 4. Discussion 4. Discussion 4.1. Merits and Limitations of the Multi-Scale Study 4.1. Merits and Limitations of the Multi-Scale Study Based on the classification of WF-AL at different scales, the county-level data can reflect the spatiotemporalBased on the classification dynamics of of regional WF-AL WF-AL at different more scales, directly the than county-level the province data/city-level can reflect data. the Countiesspatiotemporal also serve dynamics as grass-root of regional administrative WF-AL more units directly in China, than which the are province/city-level largely autonomous data. inCounties the implementation also serve as grass-root of policies administrative and the adjustment units in China, and control which of are agricultural largely autonomous and livestock in the locations.implementation This system of policies has great and advantages the adjustment for the and development control of andagricultural co-ordination and livestock of agriculture locations. and livestockThis system production. has great advantages for the development and co-ordination of agriculture and livestock production.This study identified the following limitations: (1) some county-level administrative units were subjectedThis to study slight identified jurisdictional the following adjustments limitations: or mergers, (1) some and in county-level these areas, administrative the WF-AL data units showed were abnormalsubjected fluctuations to slight jurisdictional before and afteradjustments the year or of mergers, adjustment, and and in these the interval areas, the stability WF-AL of thedata data showed was lower compared with the province/city-level data; and (2) it was difficult to obtain the data for virtual water content per unit mass of agricultural and livestock products, so the use of province/city-level average data to some extent affected the accuracy of the study results. Sustainability 2019, 11, 3693 15 of 18

4.2. Optimization of the Ecological Nodes In the overlap area at the watershed scale, the county-level administrative units were commonly associated with problems such as abnormal WF-AL compared to adjacent areas or a WF-AL much higher than the water resource capacity threshold. Therefore, it was necessary to adopt composite measurements of water resources according to local conditions: (1) counties with water shortages can be supplied by cross-regional water transfers from the Middle Line Project of South-to-North Water Division, the Yellow River-to-Baiyangdian Water Transfer Project, and the Water Diversion Project from Luanhe River to Tianjin City; and (2) in counties where the development intensity of agriculture and livestock is too high, the scale of agriculture and livestock development can be limited or reduced through detailed classiﬁcation at the village and town levels and delineation of ecologically sensitive areas for water resources within counties.

5. Conclusions Urbanization is the main direction of development in the urban agglomeration areas of the BTH region. The non-core urban counties of the 13 cities have therefore taken on part of the existing agricultural and livestock production from the core urban areas. The allocation and restoration of regional water resources has become the focus of regional agriculture and livestock development. Based on 14 typical agricultural and livestock products, we calculated the WF-AL and its density in 155 counties of the BTH region over the period 2000–2016. We also predicted the spatial distribution of the WF-AL across different precipitation years. The results showed that in areas with complex terrain conditions, the spatial differences in the WF-AL at the city level were not significant compared with those at county and terrain levels, thus making it difficult to explain the response relationship of water resources to the development of agriculture and livestock. We found that the WF-AL was clearly affected by terrain. Both the ratio of agriculture and livestock and the average value of the WF-AL were lower in the mountain area and plains area than in the buffer zone and coastal plain. Agriculture and livestock production developed rapidly in the BTH region in 2003–2005 and 2012–2014, along with significant expansion of unstable water resource development areas. In 2015–2016, a desirable balance of water resources was maintained only in Shangyi County, Zhangjiakou, Laiyuan and Fuping County, Baoding, Mentougou and Changping District, Beijing, and Jinnan, Xiqing, and Dongli District, Tianjin. Furthermore, the simulation results in different precipitation years showed that in predicted wet years, the regional water resources generally recovered, but there were still four cross-city regional water-deficient areas in the mountain area, buffer zone, plains area, and coastal plain. Therefore, taking into account the current development for agriculture and livestock in 2015–2016, we constructed a medium and long-term plan for sustainable agriculture and livestock production in the BTH region through a combination of limited development of agriculture and livestock, reservoir water transfer, and cross-regional water transfer. The goal is to achieve a balance between the optimal development of agriculture and livestock and the recovery of water resources in the BTH region. This study is of significance in that it implements quantitative evaluation and constructs an optimal plan for agriculture and livestock development in the BTH region at the county level based on the water footprint theory. It is hoped that the results of this study can effectively influence the optimal development of water resource allocation and provide a reference for the management of the city and county-level agriculture and livestock departments in the BTH region.

Author Contributions: Conceptualization, C.C., X.L. (Xiaohan Lu) and X.L. (Xuyong Li); Formal analysis, C.C., X.L. (Xiaohan Lu) and X.L. (Xuyong Li); Investigation, C.C.; Writing—original draft, C.C., X.L. (Xiaohan Lu); Writing—review & editing, C.C., X.L. (Xiaohan Lu) and X.L. (Xuyong Li). Funding: This research was funded by National Key R&D Program of China, grant number (2016YFC0503007, 2017YFC0505803), National Natural Science Foundation of China, grant number 41771531 and the National Water Pollution Control and Treatment Science and Technology Major Project of China, grant number 2015ZX07203-005. Acknowledgments: We appreciate the constructive comments of the reviewers and editors on this manuscript. Sustainability 2019, 11, 3693 16 of 18

Conﬂicts of Interest: The authors declare no conﬂict of interest.

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