The Regulation Of Floodwater And Stormwater In Guanzhong Section Of Weihe River Basin

The water resource is unevenly distributed in Guanzhong Section of Weihe River Basin,which is located in arid and semi-arid area of China. Hence, the floodwater and stormwaterresource are inundating in the rain season and scarce in the dry season, moreover, theecological base flow can’t be safeguarded. Therefore, based on the unique geological andhydrogeological conditions in Guanzhong Section of Weihe River Basin, this paper analylizedgeneral conditions, different patterns and the corresponding technical requirements in regionalscale. Afterwards, three regulation examples were chosen in terms of three typical regulationpatterns, and the water source, infiltration capacity and storage space were comprehensivelyanalyzed for each example. Then, technical solutions were designed, infiltration experimentswere conducted, the conceptual and mathematical models were built up, and the numericalsimulations for regulation were carried on for each example. Consequently, combining fieldinfiltration experiment and indoor numerical simulation, this paper made the comprehensiveanalysis for three regulation examples from the groundwater dynamics, infiltrated stormwaterand floodwater storage in aquifer and the increase of river base flow. The results are asfollows:(1) Temporal and spatial variation of water resource and river ecological base flow isremarkable in Guanzhong Section of Weihe River Basin. Moreover, the geological andhydrogeological conditions are suitable for the utilization of floodwater and stormwater inpiedmont of Qinling Mountain, river terraces and loess tableland area.(2) The Jinling River valley owns abundant water source, better infiltration capacity andgreater regulation space. Hence, it has a good underground flood regulation and storageconditions. According to the field experiments and numerical simulation results, the responseof groundwater level within the study area varies and there is a certain lag; during theinfiltration process,38.8%of the infiltration floodwater firstly fills in the vadose zone,24.9%is used for increasing the storage capacity of the aquifer, and36.3%increases runoff and baseflow of Jinling River after flowing in the aquifer for180days. Thus, this regulation andstorage instance can store longer flood storage in the underground aquifer, and rechargeaquifers as well as increase base flow of Jinling River.(3) The Taiping Alluvial Valley in piedmont of Qinling Mountain has abundant watersource, strong infiltration capacity and huge storage space, hence, it owns a strongunderground flood regulation and storage conditions. The field experiments and numericalsimulation results show that the infiltrated floodwater flows with groundwater discharges into Taiping River, so groundwater table within areaincreases modestly along the water flow.Furtheremore, during the infiltration process,22.52%of the infiltration floodwater firstly fillsin the vadose zone,8.09%is used for increasing the storage capacity of the aquifer, and69.39%increases runoff and base flow of Jinling River after flowing in the aquifer for40days. Thus,the regulation and storage instance can recharge river base flow of dry season in a relativelyshort period, and the regulation effect is remarkable.(4) Thewater depth of unconfined groundwater is rather shallow in loess tableland area,which can form huge water storage and regulation space within certain thickness. At the sametime, urban stormwater resources after processing can be infiltrated into aquifers, thereforeloess tableland area has good urban stormwater underground storage conditions. Thenumerical simulation results of different regulation schemes show that, there is certainpositive correlation between river base flow and the increase of regulation water head whenthe regulation is done by infiltration channels. What’s more, river flow and base flow increasesignificantly when extending the infiltration channels and regulation water raising the sameheight. Therefore, this regulation instance can add the groundwater as well as accelerate thedrainage of groundwater into river, which increase the river flow and base flow withinregulation area.(5) The regulation patterns in Guanzhong Section of Weihe River Basin can be dividedinto four: river vally regulation pattern, groundwater reservoirs regulation pattern in piedmontof Qinling Mountain, loess plateau regulation pattern and riverside source field regulationpattern.The above findings not only effectively relief the uneven distribution of water resourcein the study area, but also provide theoretical guidance and engineering practice basis for thesustainable development and utilization of water resource in arid and semiarid areas.