Water Resources Sustainability in the East River in South China Using Water Rights Analysis Package

Water Resources Sustainability in the East River in South China Using Water Rights Analysis Package Chen, J. and S.N. Chan Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China Email: [email protected] Keywords: East River (Dongjiang), Xinfengjiang Reservoir, water resources management, WRAP EXTENDED ABSTRACT adjusting the operation of the Xinfengjiang Reservoir. However, the storage of the reservoir at The East River in southern China is the vital water the beginning of the drought is of great source for the cities outside, such as Hong Kong, importance. Only with normal full storage, all the Shenzhen, and inside, such as Heyuan, Huizhou projected 2010 water demands from various water and Dongguan, of the region. For studying the users in the region can be satisfied. Figure 1 shows regional water resources sustainability, it is the results of releasing water from Xinfengjiang necessary to evaluate the balance between the Reservoir, and the simulation is started at the water supply capacity from the River and the water beginning of 1962. For reducing the water demand potential from those cities. The shortage, using the projected 2010 water demand understanding of water resources sustainability inside and outside of the East River basin, the would benefit the River basin management and the Reservoir water storage may reach its inactive regional socio-economic sustainable development. capacity. Storage This study investigates the water supply capacity 3 (million m ) of the East River in according to the projected 12000 100% initial storage Solid lines: WRAP simulation water demands in various water consumption 10000 Dotted line: Historical data sectors in 2010, with water rights priorities assigned to different water users inside and outside 8000 of the East River basin. With the application of 6000 Water Rights Analysis Package (WRAP) and the 4000 streamflow conditions in 1963 that was the driest 80% initial storage 60% initial storage 2000 Inactive Capacity year in the records since 1951, the water resources (4307 M m3) security of the River is analyzed. Meanwhile, for 0 evaluating the attenuation of the water shortage, 0 3 6 9 12 15 18 21 24 the effects of releasing water from the Xinfengjiang Reservoir, which is the largest Figure 1. Variation of Xinfengjiang Reservoir reservoir in the basin, is studied. storage along time for different initial water storage in the reservoir. The simulation results reveal that the water shortage can be significantly reduced with 1985 1. INTRODUCTION dealing with possible water pollutions and water shortage besides for flood control. However, The East River is located in the Guangdong studies of the water resources of the East River Province in southern China (Figure 2). It is one of with a quantitative basis are few. In this study, a the four major river systems in the Pearl River river/reservoir system management model, the Basin. The length of its mainstem is 562 km and Water Rights Analysis Package (WRAP) (Wurbs the area of the River Basin is 35,340 km2 (Chen 2004) is used to simulate the management of water and Wu 2007). resources of the East River basin. This may benefit the water basin management in future. Water resources in the East River are multifunctional. The river serves as the major 2. BRIEFING OF THE WRAP MODEL water supply to the cities and regions both inside (Heyuan, Huizhou and Dongguan) and outside The WRAP was developed by Ralph A. Wurbs (Hong Kong, Shenzhen and Guangzhou) of the and his colleagues in the Department of Civil basin. Also its water serves for the purposes of Engineering in the Texas A&M University in the navigation, ecology and environment in the river. United States in the mid-1980s. It is part of the Moreover, the reservoirs in the basin are Texas Water Availability Modeling (WAM) functioned for flood control and hydropower System implemented and maintained by the Texas generation. Therefore, integrated water resources Commission on Environmental Quality (TCEQ), management in the East River is vital and and the package has been used to simulate the necessary. management of the water resources of the river basins in Texas (Wurbs 2005). Since then, the In addition, due to the rapid economic growth and WRAP continues to evolve and the June 2006 socio-development of the region since the 1980s, version is adopted in this study. the water demand has being increasing drastically. Meanwhile the increasing water pollution tends to The WRAP simulates management of the water decrease the available water resources. The water resources of river basins under a priority-based shortage problem might be a major crisis affecting water allocation system (Wurbs 2006). In the the whole region especially during severe drought WRAP, water management and use requirements, periods in the near future. policies, practices and facilities are expressed in terms of water rights. In general, a water right in WRAP represents a water user, which refers to either a water diversion target, streamflow requirement, storage target of reservoirs or hydropower generation target. The availability of water resources are simulated using the basin hydrology information represented by sets of historical naturalized monthly streamflow sequences. A fundamental concept used in the WRAP simulation is that the available streamflow is allocated to different water rights in turn in the priority order. This is designed for the conditions in Texas, where the legal rights to the use of streamflow are generally based on the doctrine of prior appropriation. Senior water rights are protected from having their supplies diminished by later water users (Wurbs 2004). The WRAP model required the input of the following fundamental data: Figure 2. The East River Basin (adapted from Chen and Wu 2007). Control Points: They are set to define the spatial connectivity of a river system. All water rights are In the East River basin, the challenges of water associated with control points to specify their resources management include the balance locations. At any single control point, the number between water demand and supply capacity, and of water rights is not limited. the operation of water resources facilities for 1986 Basin Hydrology: They include the naturalized effects of the water right. Simulation streamflow and the net evaporation from results are recorded. reservoirs. Naturalized streamflow (in million 5. The programme moves to the next water m3/month) represents sequences of past right and repeat the above simulation streamflows adjusted to represent a specified process until the simulation for all water condition of river basin in the absence of any water rights have been finished. The actual management activities but with all other aspects of streamflow for all control points is the river basin reflecting constant present calculated for the effects of water conditions. Net evaporation is the difference diversions and reservoir release. between monthly evaporation depth and precipitation depth. The simulation algorithms of WRAP are summarized in Figure 3. Water Rights: The most basic components of a water right are its control point, priority number and the target diversion, hydropower generation or Determining diversion/streamflow target streamflow requirement. However, the WRAP model also provides high flexibility for modelling Determining amount of water available complex system configurations and operations. to the right Making diversion and reservoir releases Reservoirs: The input defines the reservoir properties. They include the different storage capacities (dead, conservative and flood control) Adjusting streamflow at all CPs and storage-area curve. The net evaporation rate is right water next to Move Recording simulation results of the right used for determining the net water output from the reservoir surface. Figure 3. WRAP Simulation Structure. In the WRAP simulation, all input data, including control points, natural streamflow, evaporation rate Simulation results can be extremely voluminous if and water rights are read in by the programme there are large number of water rights and a long SIM. The water rights are then arranged in priority hydrological period of the river. The auxiliary order. Water allocation and management are programme TABLES can rearrange these outputs modelled by accounting procedures within a water and carry out further calculations to present the right priority loop. As each water right is results in a more useful way. The common outputs considered in priority order, the following tasks are are volume of water shortage for each water rights, performed: reservoirs end of period storage and the regulated flows. 1. The monthly water diversion, streamflow requirements and hydropower generation 3. INPUTS TO THE WRAP MODEL is set according to the input value 2. The amount of water available to the 3.1. Control Points water right from streamflow is determined based on the available streamflow, after In this study, control points are set to represent the the appropriation to more senior water reservoirs and locations of water intake in the East rights considering its control point and all River. Four control points are set up to represent downstream control points. the six cities which extracts water from the River (Figure 2). Control points are set for Heyuan, 3. Water use requirements are met subject to Huizhou, Taiyuan and Shilong. Taiyuan is the water availability following specified pumping station where Hong Kong and Shenzhen system

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