Your search found 5 records
1 Roost, Nicolas; Cui, Y. L.; Xie, C. B.; Huang, B. 2003. Water supply simulation for improved allocation and management. In Pereira, L. S.; Cai, L. G.; Musy, A.; Minhas, P. S. (Eds.), Water savings in the Yellow River Basin: Issues and decision support tools in irrigation. Beijing, China: China Agriculture Press. pp.275-290.
(Location: IWMI-HQ Call no: 631.7 G592 PER Record No: H040073)
2 Roost, Nicolas. 2003. Strategic options analysis in surface irrigation systems: integrated modelling for efficient, productive and equitable water use. Thesis no.2641 (2002) presented at the School of Architecture, Civil and Environmental Engineering of the Swiss Federal Institute of Technology (Lausanne) to earn the title of Dr. Es Technical Sciences in the field of Environmental Sciences and Engineering. 128p.
(Location: IWMI-HQ Call no: D 631.7.1 G000 ROO Record No: H036071)
(Location: IWMI HQ Call no: 631.7.1 G592 ROO Record No: H040568)
The Zhanghe Irrigation System (ZIS), in Central China, has drawn attention internationally because it managed to sustain its rice production in the face of a dramatic reallocation of water to cities, industries and hydropower uses. Ponds, the small reservoirs ubiquitous in the area, are hypothesized to have been instrumental in this. Ponds are recharged by a combination of return flows from irrigation and runoff from catchment areas within the irrigated perimeter. They provide a flexible, local source of irrigation water to farmers. This paper assesses the storage capacity and some key hydrological properties of ponds in a major canal command within ZIS. Using remote sensing data (Landsat and IKONOS) and an area–volume relationship based on a field survey, we obtained an overall pond storage capacity of 96 mm (per unit irrigated area). A comparative analysis between 1978 and 2001reveals that part of this capacity results from a very significant development of ponds (particularly in the smaller range of sizes) in the time interval, probably as a response to rapidly declining canal supplies. We developed a high-resolution digital elevation model from 1:10,000 topographic maps to support a GIS-based hydrological analysis. Pond catchments were delineated and found to extensively overlap, forming hydrological cascades of up to 15 units. In a 76-km2 area within the irrigation system, we found an average of close to five ‘connected’ ponds downstream of each irrigated pixel. This high level of connectivity provides opportunities for multiple reuses of water as it flows along toposequences. A fundamental implication is that field ‘losses’ such as seepage and percolation do not necessarily represent losses at a larger scale. Such scale effects need to be adequately taken into account to avoid making wrong assumptions about water-saving interventions in irrigation.
(Location: IWMI HQ Call no: 631.7.1 G592 ROO Record No: H040569)
This paper investigates the impacts of farm ponds in a context of declining supplies in a major canal command within the Zhanghe Irrigation System (ZIS), in Central China. As dam supplies have been diverted to higher-valued uses (hydropower, cities and industry), farmers have responded by constructing small storages within their fields. These farm ponds have given them sufficient flexibility in water supply to practice varying forms of alternate wetting and drying irrigation for rice without compromising yields and incomes. Ponds are recharged by a combination of return flows from irrigation and runoff from catchment areas within the irrigated perimeter. Various scenarios of water supply incorporating the main reservoir, in-system reservoirs, farm ponds and irrigation practices were simulated using the OASIS model. OASIS integrates surface and groundwater flows, and contains a crop growth module to aggregate the impacts of different water management regimes. The modelling and sensitivity analysis show that further reductions in main reservoir supplies will have a negative effect on rice production in dry and average years, and that ponds have played a crucial role in adapting agriculture to reduced canal supplies. The flexibility allowed by the ponds has resulted in increased water productivity, except in high rainfall years, but net depletion has not decreased, as local supplies have substituted for water from the main reservoir. The study demonstrates the importance of properly accounting for return flows and the necessity to understand crop production in relation to the actual depletion of water (as evapotranspiration) within an irrigation system.
5 Roost, Nicolas. 2003. Strategic options analysis in surface irrigation systems: integrated modelling for efficient, productive and equitable water use. Thesis no.2641 (2002) presented at the School of Architecture, Civil and Environmental Engineering of the Swiss Federal Institute of Technology (Lausanne) to earn the title of Dr. Es Technical Sciences in the field of Environmental Sciences and Engineering. 128p.
(Location: IWMI-HQ Call no: D 631.7.1 G000 ROO c2 Record No: H043655)
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