Main contends 1) Overview on groundwater resources

Transcription

1 GROUNDWATER ISSUES IN VIETNAM (VN) Main contends 1) Overview on groundwater resources 2) The situations of exploitation and utilization of groundwater 3) The situation i of groundwater management 4) Some main problems and challenges I. Overview e on groundwater in Viet Nam Groundwater resources (GWR) of Viet Nam are quite plentiful. Total natural dynamic reserves of GW in the whole country is about 60 million m3/day. The main water bearing formations consist of: (i) The porous water bearing formations in the Quaternary and Neogene sediments - Widely distributed ib t d on the Northern and Southern Delta, and along the coastal areas of VN, - Thickness varies from several tens of meters to m. Particularly, the Northern and Southern Delta are the two regions with potential GW being exploited mainly for urban and rural areas water supply and most industrial activities. - The total t volume of GW extraction ti in these two deltas is estimated about 3-4 million m 3 /day.

2 I. Overview e on groundwater in Viet Nam (cont.) (ii) The water bearing formations in limestone - Distributed mainly in the northern mountainous areas of Vietnam, with an area of about 50,000km 2. - In these areas, due to high terrain and scarcity of surface water, groundwater is the main source of water supply for drinking and domestic purposes, as well as productions and economic development of the areas. - Besides, groundwater in these areas is also the major source for rivers during dry season. - The module of the underground d flow in limestone is about l/s.km 2 I. Overview e on groundwater in Viet Nam (cont.) (iii) The water bearing formations in basalts - Large distributed ib t d in the Central Highlands. - There are many zones and aquifers in the basalt formations. - The module of the underground flow in basalt is nearly 10 l/s.km 2. The extraction ti rate in wells can reach 100 m 3 /h. - Currently, GW in the basalt is the primary source for drinking and domestic purposes of people in the areas, and also an important sources of irrigation for coffee in the Central Highlands.

3 I. Overview e on groundwater in Viet Nam (cont.) (iv) Groundwater in hard rock formations (including sedimentary, and magmatic rocks) - Distributed in many areas of the Central, Central Highlands and northern mountainous midland, in fracture of the hard rock. - In these formations, the water storage capacity is not high, some even poor, but it plays an important t role for domestic water supply of households in rural areas because these regions are drought prone areas of VN. II. The situations of exploitation and utilization of GWR 1) Water supply for urban areas - At present, about 40% of the water supply for urban areas is GW. The urban areas using most GW are Ha Noi (with nearly 1,000,000m 3 /day); Ho Chi Minh City (about more than 500,000m 3 /day)... - Total extraction volume of GW for domestic and industries in urban areas is estimated t about 1 billion m 3 /year in average.

4 II. The situations of exploitation and utilization of GWR 2) Water supply for domestic purposes in rural areas: - Nearly 80% of water for domestic purposes of rural areas is from GW, and over 70% of rural population in Vietnam depends on GWR. - The GW extraction in rural ral areas are mainly from tube wells, dug wells and springs. II. The situations of exploitation and utilization of GWR 3) Water supply for irrigationi - GW is used for irrigation mainly for some crops with high h economic values such as coffee, and peppers in the Central Highlands and litchis in some areas of VN. - The total volume of GW used for irrigation is estimated about 600 million m 3 /year. - Especially in the dry season, GWR is an important source for drinking and domestic purposes, irrigation, livestock, aquaculture, etc in many areas of VN.

5 III. The situation of GW management 1) The GWR management has been executed in Viet Nam since 1998 (on issuance of the Water Law). - Legal document systems for GWRM includes: Water Resources Law; National Strategy on Water Resources The documents under Water Resources Law + Decree on licensing for exploration, exploitation and utilization of WR and waste discharge into the water resources; + Decree on administrative sanctions in WR sector; + Regulations on licensing for drilling; + Regulations on GW protection (for excavation and drilling activities, water extraction, constructions of underground projects, etc.). III. The situation of GW management - The oganization for WR management has been established from central to district level. - The National GW monitoring Network has been developed for 3 regions: the Northern delta, Southern delta and Central Highlands. In coming time, the Goverment will upgrade the Network to ensure the capacity of observation for changes in quantity and quality of groundwater, especially in the context of climate change and sea level rise.

6 IV. Some main problems and challenges (i) Pollution of GW: - The quality of GW are generally good and stable, to meet the different purpose. However, the rapid urbanization and economic development in the past years have enormous impacts on water resources in our country y(both surface and dgroundwater). - Particularly, GW in the shallow aquifers in urban areas of Ha Noi, Ho Chi Minh City and other cities as well as in the industrial parks has been contaminated with organic compounds with different levels. (ii) GW level declined: Due to the excessive exploitation of GW in the past years, the water tables in the recent years in some urban areas with high rate of groundwater extraction, such as Ha Noi, Ho Chi Minh City, Ca Mau, Bac Lieu, and Soc Trang (see the following figures). (iii) So far, the planning for groundwater exploitation and protection has not been developed; the awareness of people in water resources protection is still limited. (iv) In addition to the above-mentioned problems, characterized by the geographical conditions of Vietnam, a country bordering the sea, the altitude of the deltas are low. Therefore, the GWR of Viet Nam have been predicted to be greatly influenced by sea level rise due to climate change.

7 The situation of depression of groundwater tables in Ha Noi area diön tých phôu h¹ thêp DiÖn tých phôu <0m : Km2 DiÖn tých phôu <-8m : Km2 DiÖn tých phôu <-14m : Km2 chødén P.41 Lç khoan quan tr¾c 2 - êng thuû ¼ng p The situation of depression of groundwater tables in some monitoring points in Ha Noi n- í c, m Mùc P41a Q63a -26 1/ 93 1/ 94 1/ 95 1/ 96 1/ 97 1/ 98 1/ 99 1/ 00 Thêi gian

8 The situation of groundwater extraction in Ho Chi Minh City Extraction volume of Ho Chi Minh City in time Ba Mieu aquifer

9 Changes in water levels and discharge volumes in time aquifer QI-III