Water conservation zones (WCZ) are an important part of water resource management strategies. They have been developed to provide water for farming and reduce downstream water quality degradation. In addition to making crop production possible in dry areas, water conservation zones minimize soil erosion, improve soil water content and enhance soil fertility and quality.
The management of WCZ has been a challenge due to the poor understanding of the relationship between upstream land uses and the dynamics of water in WCZ. Land use and hydrological processes occurring in the upper catchment often affect water and nutrient capture and storage in these zones. Evaluation of sources and sinks of water, and water and nutrient budgets for WCZ as influenced by upstream land use activities is important for optimizing the capture, storage and use of water and nutrients for farming.
The CRP evaluated three types of WCZ, namely: (1) water and nutrient storage for downstream irrigation use and downstream water quality (farm ponds) in Iran, Lesotho and Tunisia, (2) in situ crop production (wetlands including riparian wetlands) and downstream water quality in China, Nigeria and Uganda, and (3) plantation and fuel wood production (riparian buffer zones) and downstream water quality (riparian buffer zones) in Estonia and Romania.
18O, 2H and 15N stable isotopic signatures in soil, water and plants are ideal for identifying sources, sinks, dynamics and factors influencing water and nutrient capture and storage under a wide range of environmental and socio-economic contexts and spatial scales. This facilitates the contribution of these farm wetlands for water harvest and nutrient removal to be characterized within the WCZ. The gathered information enables scientists to assist farmers to identify the ideal locations in the landscape to construct wetlands to capture the extra water and nutrients to be stored for future use.?
In Iran, 30 Ab-bandans ponds in the Caspian lowlands, occupying approximately 3% of the catchment area (10,400 ha), captured 7 million m3 of water together with 86 tonnes of N, and 17 tonnes of phosphorus. This water and associated nutrients helped to increase the irrigation area from 730 to 1,500 ha and rice production from 2,560 to 5,050 tonnes. In Northeast China, wetlands were used to cultivate 10 tonnes/ha of rice without nitrate contamination of surface and groundwater, through the optimization of water conservation. The riparian buffer zones in Estonia, featuring alder trees, the wood from which is used for fuel, remove between 170 and 350 kg N/ha/year and reduce nitrate contamination of downstream water by 50%. Most of this removal was accompanied by the denitrification of N2 gas, thus reducing greenhouse gas emission to the atmosphere.
A manual of guidelines has been published as a result of this CRP to support WCZ in developing wetlands in agricultural catchments as a part of a strategy to provide water for farming and reduce downstream water quality degradation.
Researchers from China, Estonia, France, Iran, Lesotho, Nigeria, Romania, Tunisia, Uganda and the United States participated in this CRP.
For more information, please see the CRP description:
http://www.dgdingfa.net/projects/crp/d12010
?