Influences Of Land Cover Changes On Floods And Water Resources

Land cover changes due to heavily human activities result in floods and changes of water resources in quantity and quality, which has been a serious problem for nowadays society. Study of impacts of land cover changes on floods and water resources is very important for flood-control, reduce of disasters and sustainable utilization of water resources. This paper mainly addresses the following issues:(1) Based on analysis of mechanism of non-control factors, such as forest, urbanization, and water and soil conservation, influencing floods, simulation models are established for estimation of impacts of non-control factors on floods in several selected catchments.(2) For estimation of influences of hydraulic engineering (control factors) on floods, a reservoir regulation model is established based on calculation units controlled by each reservoir and reservoir system co-operations. Then, a fundamental suggestion for estimation of impacts of both control factors and non-control factors on floods is presented and a comprehensive model for this estimation is developed.(3) Relatively stable conditions and standards of a dam system, and mechanism of increasing efficiency of water resources utilization by a dam system are studied.(4) According to analysis of water resources characteristics of the dam system, following conclusions are obtained: amount of yearly available water resources of the dam system presents uncertainty; Water resources utilization by the dam system should focus on fully utilization of rainfall, runoff and flood; meanwhile, water resources exploration of the dam system should reach the objective of maximum economic benefit in years; a modeling system for water resources utilization and exploration by the dam system is established on the basis of reasonable investment and above objectives.(5) Impacts of the dam system construction on utilization and exploration of water resources in a specific region from Hekouzhen to Longmen in Yellow River are studied. The results show that after reaching relative stableness, the dam system located in the region is able to supply 1.6 -2.9 billion m3 of water for agriculture. Most annual runoff in approximately half of years can be stored and utilized, and the replenished soil moisture is 5.2 billion m3 above in more than half of years. Impacts of the dam system construction on water resources in the lower Yellow River are studied.