Available Water Resources.
A subjective assessment of the available reserves water resources of the country has been made by using data based on characteristics of water bearing formations. The mean annual rainfall over the country amounts to about 191.4 x 10' m' and large volume of it is lost to evaporation due to arid climatic conditions prevailing in the region. It is estimated that the mean annual surface water in the two rivers, Jubba and Shabelle, is about 7.8 x 10 m³. This constitutes 1.31% of the present water resources potential in the country. In addition, the amount of groundwater stored in the alluvial aquifers is estimated at about 33.6 x 10' m³ with annual replenishment of about 288 x 10 m³. The volume of groundwater stored in these aquifers is equivalent to about 5.7% of total groundwater reserve in the country. Moreover, the potential volume of ground- water in the principal confined aquifers amounts to about 560.6 x 10' m³ and their corresponding recharge volume over the outcrop area is 962 × 106 m³ per year. The volume of groundwater reserve in the principal aquifers constitutes 94.3% of the total volume of groundwater potential estimated in both confined and unconfined aquifers. Thus, from these estimates, one can arrive at 7.8 x 10 m³/year of surface water from the rivers and proven reserve potential of 594.60 x 10 m³ from the confined and unconfined aquifers which can be replenished by normal rainfall, whose volume is 1250 x 106 m³ per year. Table 4.1 shows a summary of available water resources in the country and their corresponding source. The results of these calculations show the presence of large amount of water in the country in spite of difficulties of water shortage in some parts. These shortages are due to lack of development of the aquifers and of a proper plan of water distribution. The volume of water available in the country is enough to meet the demand for water and can be used to convert the suffering nomadic people to settled agricultural society and to reduce the chances of famine in the country.
shows a summary of available water resources in the country and their corresponding source.
The demand for water as presented here comprises the demands for domes- tic and livestock population, and agricultural and industrial purposes. In an attempt to cover the water requirements for purposes other than those already mentioned, the total demand could be increased by the required percent. How- ever, the estimation of water demand is based on the rate of consumption for the various use sectors in accordance with their modified growth and development within the projected period of twenty years.
4.2.1. Domestic and Livestock Water Demand.
About 70% of the Somali population are nomadic and the remaining 30% are inhabitants of the large towns and villages. Water consumption by rural inhabitants depends on the proximity to water sources. Consumption increases markedly if the distances traveled to obtain water is about a couple of
The expected future water requirement for both domestic and livestock during this projected period is shown in Table
Agricultural Water Demand.
The requirement of water per unit of agricultural production depends on the climate, type of crops, method of irrigation practiced, adequate water supply and level of irrigation management. At present, the irrigated land in the country is about 80,000 hectar which occupies about 7.3 % of the cultivated land
(Table 1.1). The major crops which are produced from this 7.3% of the cultivated land
are classified in to two groups: perennial and seasonal. 30% of this land is used to produce perennial crops (banana, sugar cane and citrus) while the remaining 70% is used to produce maize, sesame, rice and vegetables of various types. Under the present conditions, the average water requirement of the perennial crops is estimated as 13 x 103 m³/ha per year (Lahmeyer, 1987). Thus, the total amount of water required by the perennial crops produced from the 30% of the irrigated land is estimated as 312x 10" m³/year. The seasonal crops occupy about 70% of the total irrigated land and are harvested two times per year (if all involved conditions remain normal). The average water consumption per hectar of these seasonal crops is about 8x 103 m³ per season (Lahmeyer, 1987). Therefore, the total volume of water required per year for these seasonal crops is estimated as 896 x 10 m³. At present, the total water demand per year for the irrigated land amounts to 1201 × 10" m³.
About 92.7% of the cultivated land is of rain-fed type producing sorghum and other crops which are extensively dependent on rain water. The develop- ment of groundwater for irrigation in those areas is practically negligible and the rivers are too far away to get water from. Therefore, the efficiency of production is very low. However, if the irrigated land is increased by 10% per year during the projected period and all involved conditions remain normal, the total requirement of water for irrigation will be about 8.14 x 10 m³ in the year 2010 (Table 4.2). In addition, the total volume of water estimated for the irrigated land is not under consumption throughout the year, but it is used as a supplement when wet conditions decrease during the dry season. Presently, irrigated.
the total requirement of water for irrigation will be about 8.14 x 10 m³ in the year 2010 Table.
The development of the industrial sector in Somalia is considered minimal because only a small number of factories are operating in the country and their consumption of water is marginal. Even if the industrial water demand grows considerably within the coming years, the quantity of water required will always remain negligible when compared to the other sectors of water consumption. Therefore, it is assumed that future industrial water demands will be met with- out any loss to other sectors demands.
Calculation of Water Resources Demand.
Water demand for domestic and livestock.
A weighted average of consumption figure of 30 l/d per capita for rural population, 70 l/d per capita for inhabitants of towns and village (domestic consumption) and 20 l/d per capita for livestock population is used for assessment of water demand in a projected period of twenty years (1990-2010). These conservative numbers are referenced from the previous studies conducted by Louis Berger International, Co. (1985) and Lahmeyer (1987) in some parts of the country.
Domestic Demand for Water.
In 1990, the total population of Somalia was 8.2 million. Assuming a modified growth of 2.5% per year, the demand for water is calculated and presented in Table
Livestock Water Demand.
The total livestock population in Somalia was 46,344, 132 in the year 1990. The average growth of livestock population is about 12 % per year (Study on water points in Gedo and Bakool, Somalia, 1989). The demand for water is calculated and presented in Table
Agricultural Water Demand.
The present Irrigated land is about 80,000 ha. 30% of these land is used to produce perennial crops while the remaining 70% produces seasonal crops. The future water demand of this irrigated land is as follows.
1. 30% of the irrigated land is about 24,000 ha. An average per hectar demand of water for perennial crops is about 13× 103 m³/year. Thus, the total demand per year is about 312 × 106 m³ /year.
II. 70% of the irrigated land is about 56,000 ha. An average per hectar demand of water for seasonal crops is about 8 x 103 m³/season. Hence, the total
demand per year is about 896 x 10 m/year. If the irrigated land is increased by 10% per year (beautiful Somalia, 1980) and all involved conditions remain nor- mal, the growth of water demand for irrigation will be as shown in Table .
Comparison Between Available Water Resources and Demand for Water
Comprehensive analysis of the available water resources and demand for water is made and, as estimated in the previous sections, it is clear that the present available potential reserves exceeds the consumption of water and satisfy the demand during the projected period.
Tables 4.1 and 4.2 show the results of projected water demand according to the consumption of various sectors and readily available water resources.
It is evident that both surface water from the rivers and groundwater from the aquifers are adequate to meet the projected demand, but will not be sufficient beyond the year 2042 if the growth of water demand continues to increase with same ratios.
Development and Distribution.
The available groundwater resources are limited and will not be sufficient to satisfy the growing demand, if the country is to depend solely on groundwater, unless new measures of ground- water strategies are established and implemented in the near future.
This is because the long term future prediction (after 2010) shows early depletion of groundwater, despite expected future annual recharge (to the aquifers) and sur- face water being included in the reserve during the prediction.
This future pre- diction is based on the assumption that the net withdrawals are equal to the future demand of the country at the beginning of the prediction (year 2010).
The demand will increase at about 3.42% per year of the available groundwater in the country after the beginning of prediction
The available water resources satisfy the demand for water. while this indicates that availability of water is greater than the demand, it does not mean that it is developed and distributed evenly, nor does it mean that it is distributed at the specific locations where it is most needed.
The development of existing aquifers is minimal because wells are scattered and the distance between a group of wells to another group of wells in the same aquifer could be in an order of 60 to 70 kms, especially in the northern and central regions where aquifers are deep.
. In order to overcome this problem, a scheme of distribution of surface water from the rivers which pass through the southern part of the country and dump large volumes of water to the Indian Ocean is required.
This scheme should be achieved either by means of pipelines or diverting the flow towards the grazing land.
Of course, both alternatives are not feasible at the present eco- nomic standard of the country.
Further efforts should be put into exploration and development of groundwater from the suspected deeper hydrogeological basins.
, more effort and investment should be put into the implementing a system of series of small dams and embankments which could store rain water in areas where water is scarce.
This can sustain the need for water in remote nomadic areas of the country, where some basic agricultural activity could be started, and nomadic life could yield to a more sustaining agricultural settlements.
