Sand Mining Research Of The Nandu River Downstream Based On The Ecological Health Of The Basin

With the accelerated pace of urban construction in Hainan province, demand forbuilding sand increased rapidly, river sand prices soared. This led to the illegal andunauthorized sand mining continue to emerge at Nandu River downstream segmentand sand mining activities made great thread to the flood safety, alluvial process ofriver, quality of the river water. Under the premise of ensuring the sustainabledevelopment of the watershed ecological health and regional economic, how tocontrol of artificial sand mining activities, and provide a scientific basis for thedivision of the sand mining function area is a topic of much-needed research.This paper describes the current sand extraction status planning and managementsituation and existing problems along the44km long of River from Yongfa townhighway Bridge to Longtang dam. Based on measured terrain, hydrological data ofthe river flow, developed a mathematical model of sediment modelling, and verify thereliability of the model. The model is applied to numerical simulation studies of theriver for different boundary conditions. The main study includes several aspects:(1) By simulating the flood in August2010, studied the entire river water level,flow field, discharge per unit width, water depth distribution, and sediment transportcharacteristics;(2) By setting1000~8000m3/s of upstream discharge, studied the variation of theriver hydrodynamic characteristics and sediment transport characteristics with thevariation of the flow;(3) Studied the backwater and flow field near the bridge (pier);(4) Studied the water level and flow field distribution characteristics at river bend;(5) Studied the water surface and velocity distribution characteristics at Tributary;(6) Studied the various impact of the proposed works (levees) to the flow andsediment characteristics of the river;(7) By artificially setting several specific sized sand mining pits in the river,studied various impacts of sand mining;(8) A simulation of the river over an extended period of suspended load, bed loadtransport and morphology change of river have been conducted. According to theresults, provide a scientific basis for the division of mineable area of sand, prohibited area of sand-mining. Reasonable modifications have been made to the existing sandmining plan.