FORECASTING UNDERGROUND WATER RESOURCES IN THE NORTHEN DELTA FOR THE 2017 – 2022 PERIOD
Abstract
The Red river delta plain (RRDP) has an area of nearly 17,000km2, located in the territory of 12 provinces and cities in the north that is the key economic area, the population is very crowded with high water demand, so groundwater (GW) is being exploited strongly for the different needs. The RRDP is structured by Quaternary sedimentary rocks with thickness ranging from about 10m in the fringe to over 100 in the coastal area. Due to phasing, the Quaternary sediments are divided into two porous aquifers: the upper Holocene (qh) and the lower Pleistocene aquifer (qp). GW in the qh aquifer is suitable for small scale and scattered scale of water supply for rural areas; GW in the qp aquifer can be supplied for public water supply for urban and industrial areas. To control and forecast the variation in groundwater resources, since the 1990s the GW monitoring network has been established. Up to now, there are 12 stations, 106 sites with 198 observation sites, which are continuously monitored for groundwater dynamics. The results of the observation are the basis for predicting the fluctuation of water resources in the period 2017-2022. On water level, for the aquifer qh, the water level tends to decrease very small, accounting for about 8.33% distributed in the inner city of Hanoi and Hai Phong. The remaining area, the water level tends to stabilize. For the qp aquifer, nearly half of the aquifer area tends to decline at a rate of 0.1 to over 0.4m/yr. These are areas that GW has been heavily exploiting. In terms of total dissolved solid, qh aquifer: only a very small area, about 50km2 in the provinces of Hung Yen, Bac Ninh, Thai Binh, Nam Dinh, Ha Nam, Quang Ninh is likely to be salt intrusion. The qp aquifer, by 2022, the saline intrusion area may be about 640 km2, accounting for 5.1% in Hai Phong and Bac Ninh, Hai Duong, Thai Binh, Nam Dinh and Ha Nam provinces. Water levels tend to decrease and salinity intrusion in the qp aquifer increases may due to trongly exploitation.
