this study have focused on the Phetchaburi province and particularly the region surrounding the Sirindhorn International Environmental Park. The WEAP model simulates the main components of both the natural and managed components of the hydrologic cycle, e.g. overland flow, percolation, evapotranspiration, groundwater recharge, river flows; reservoir storage and operations, hydropower generation, irrigation diversions, water demands and deliveries for human uses (municipal, industrial, environmental, and agriculture). The WEAP-Phetchaburi model includes the main rivers of the Phetchaburi and Prachuab Khiri Khan provinces of Thailand, with Fig.3 showing the extent and inter-connectedness of the model. The water systems are connected through a series of both natural rivers and man- made canals, whose inflows originate from 60 WEAP catchment objects covering roughly 12,000 km2 of land area, with an average size of 200 km2, a median area of 80 km2, and maximum size of 2000 km2. Each catchment is broken into representative land use/land cover classes described including forests, grasslands, agriculture, and urban. The catchments were defined by important hydrologic and water infrastructure attributes, such as tributary rivers, reservoirs, diversions, and agricultural areas (Table 1). Table 1 Characteristics of the WEAP model for the Phetchaburi River Spatial Domain and characteristics. Model covers the Phetchaburi and Prachuapkhrii Regions, and includes the 31 largest rivers, 17 reservoirs, 11 municipal demands, and 50 sub-basins, of which 20 include irrigation (field crop, perennial, aquaculture, paddy field). The major canals that deliver water to the eastern coast are included. Time Horizon Model runs on a daily timestep and uses the historic period 1999 to 2005 for calibration and validation; the future period is 2020 to 2040. Modeled Components Model simulates the hydrologic cycle, generating streamflow to the river and canal networks. Demand includes environmental, municipal and agricultural demands. Groundwater and surface water are primary supplies to region. Fig.4 shows results from model calibration and summarizes important attributes of the WEAP- Phetchaburi model for the historic period 2000 through 2005, with 1999 used as a spin-up year to stabilize the hydrologic processes such as soil moisture. Fig. 4 includes municipal- industrial and irrigation demands for zones A3, A4 and A5 (see Fig. 3 to identify those zones) and the source of supply for those same zones. The figure shows that agricultural use and imported water dominate the water systems of the region. Fig. 4 also shows the simulated flows for the Phetchaburi River above and below the Phetchaburi Dam diversion plotted as a frequency distribution (bottom left), and the diversion from the three primary canals (see Fig. 3). We estimate that the total water demand in the Phetchaburi and Prachuab Khiri Khan Provinces, with a total population of about 1,000,000 and an agricultural area under irrigation of more than 350,000 ha. We estimate total water demand in the region of between 7,000 MM3 and 10,000 MM3. A comprehensive analysis of this region was beyond the scope of this study, and so we focused our analysis on the southern coastal region of the Phetchaburi province that includes the Sirindhorn International Environmental Park. We estimate annual water use in this region of about 170 MM3 or just about 2% of the total water demand for the two provinces. 244 Proceedings of the International Conference on Climate Change, Biodiversity and Ecosystem Services for the Sustainable Development Goals (SDGs): Policy and Practice 27-29 June 2016, Cha-am, Phetchaburi, Thailand
Proceedings of International Conference on Climate Change, Biodiversity and Ecosystem Services for the Sustainable Development Goals : Policy and Practice 27-29 June 2016 at the Sirindhorn International Environmental Park, Cha-am, Phetchaburi, Thailand
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