3.4 – Sensitivity of Water and Lakes

Water resources have been classified into surface and groundwater. In terms of sensitivity, water resources will be affected in terms of quantity and quality by the oil development and its related developments.

3.4.1 – Surface water sources

There are three major lakes within the graben; Lake George, Lake Edward and Lake Albert. While bathymetric studies have been undertaken on Lake Albert, the levels of Lake George and Lake Edward are unknown. Also within the graben, there are many rivers and streams as presented in the map below.

Surface water sources within the graben are very vulnerable to contamination and are therefore categorized as highly sensitive. Sensitivity reduces with distance from the respective sources.

3_4_1_map_18

 

 

3_4_1_map_19

 

3.4.2 Groundwater

The Ugandan rural population depends on groundwater for domestic purposes as a result extensive groundwater development has taken place in the Albertine graben. The map in figure 3 shows the extent of groundwater development in this area. Just like sensitivity of surface water sources, the sensitivity of each of these sources is highest at the source and reduces away from the source.

3_4_2_map_20
3.4.3 Groundwater resources sensitivity

This map was prepared on the basis of the level at which water is first intercepted if one is to drill in that area (first water strike). It is a general indication of the level of the first aquifer underlying the graben.
The first water strike map gives an indication of how easily groundwater can be contaminated. The shallower the groundwater the more susceptible it is to contamination. Therefore a shallower water strike is more sensitive than deeper water strike.

3_4_3_map_21

The map was prepared using data from borehole logs and springs in the Albertine graben.

The description of sensitivity of first water strike is divided into three ranks as shown in table below.

 

Table 2:                Sensitivity of groundwater resources

Depth to Water Strike in meters below ground level Description of sensitivity Rank

1 – 15

High

9

15 – 30

Medium

7

> 30

Low

3

From analysis, 80% of the area has high sensitivity, 8% has medium sensitivity and 12% has low sensitivity. The ranks are given to the respective classes in terms of sensitivity, the higher the sensitivity, the more vulnerable the resource to contamination therefore the higher the rank.