Can groundwater secure drinking-water supply and supplementary irrigation in new settlements of North-West Cambodia?

Abstract

Since the end of the Cambodian Civil War in 1998, the population of the Oddar Meanchey province has drastically increased despite the lack of adequate infrastructure, including basic amenities such as drinking-water supply. To improve the access to drinking water, governmental and aid agencies have focussed on drilling shallow boreholes. The use of groundwater for irrigation is also a growing concern to cope with the occasional late arrival of the rainy season or to produce food during the dry season. Since the groundwater resource in the province has not been documented, a 4-year study was undertaken (2011)(2012)(2013)(2014), aiming to estimate the capability of groundwater to supply domestic needs and supplementary irrigation for rice production. Aquifer properties were estimated by combined use of hydrogeological techniques with the geophysical magnetic resonance sounding method. Groundwater storage and recharge were estimated based on new developments in the application of the geophysical method for quantifying specific yield. The median groundwater storage of the targeted sandstone aquifer is 173 mm, the recharge is diffuse and annually ranges from 10 to 70 mm, and the transmissivity is low to medium.Simulations of pumping indicate that the aquifer can easily supply 100 L of drinking water per capita daily, even considering the estimated population in 2030. However, the shallow aquifer can generally not deliver enough water to irrigate paddy fields of several hectares during a 2-month delay in the onset of the monsoon.

Regional Assessment of Groundwater Recharge in the Lower Mekong Basin

“…The comparison of our results with previous studies undertaken in the LMB (Section 5.2) has highlighted an overall general agreement: absolute relative differences between these previous local assessments and our recharge rates in these locations are yielding an average of 32% excluding the two case studies in North and Southeast Cambodia where this percentage exceeds 100 [53,54]. These higher discrepancies likely result from two main factors: (i) the presence of local clay deposits in the surveyed sites; (ii) the sparse network of river gauging stations in Cambodia not monitoring these specific sites, thus not allowing our model to capture this sub-regional recharge constraint.…”

“…Broader-scale groundwater recharge assessments was performed over 15,000 km 2 in central Cambodia [52], yielding 448 mm/year from the SCS runoff curve method, aligned with Q B estim (464 mm/year) and slightly greater than Q B pred (278-357 mm/year) in this area. In Northwest Cambodia, groundwater recharge rates were estimated over 3375 km 2 of sandstones from Upper Triassic to Lower Cretaceous, using the water-table fluctuation method and the stable isotopes analysis from 12 piezometers [53]. Recharge rates of 10 to 70 mm/year, lower than our estimations in this area (200 mm/year), were explained by clayey soils overlying sandstone, whose presence can highly vary at the scale of few tens of meters.…”

“…Our estimations of recharge rates can also be compared with more localized studies [8][9][10][50][51][52][53][54]. Baseline recharge rates estimated with the HELP3 hydrologic model and projected under the ECHAM GCM A2 and B2 scenarios were used to predict groundwater recharge rates in the Huai Khamrian catchment in Northeast Thailand, yielding values of 253, 351, and 329 mm/year, respectively [8].…”

Characterizing the Water Storage Capacity and Hydrological Role of Mountain Peatlands in the Arid Andes of North-Central Chile

“…A significant contrast between peat and the underlying mineral soil will likely occur due to the markedly different physical characteristics of organic versus inorganic sediments [53]. Electrical resistivity depends on the water and clay content [50,54], as well as the media consolidation degree (Table 1).…”

Determining the Discharge and Recharge Relationships between Lake and Groundwater in Lake Hulun Using Hydrogen and Oxygen Isotopes and Chloride Ions

“…When analyzing the relationship between δD and δ 18 O in different water bodies, most researchers have utilized either the Global Meteoric Water Line (GMWL) [6] or the Local Meteoric Water Line (LMWL), depending on the data collected by the Global Network of Isotopes in Precipitation (GNIP) sites that are nearest to their study areas. However, the atmospheric water lines in different regions may vary due to differences in the many factors that affect the stable isotope fractionation from the water vapor source to raindrops [7].…”