Best Practice for Water Risk Assessment
Environmental risk assessment on the volume of the water resource system and water consumption for making administrative decisions.
The problem of water deficiency is usually caused by high population density, active water usage, water pollution, and artificial regulation of rivers. There are many examples of successful water deficiency solutions across the world: construction of the controlled irrigation system ‘Subak’ on the island of Bali which optimized water consumption; water diversion from neighboring rivers by means of artificial canals construction as it was done for the Moscow River. However, none of these measures offer an ultimate solution to the problem as the population continues to grow in these regions.
In order to predict future changes it is necessary to know how the water consumption structure was changing in the past and how it functions currently. This article shows the analysis of long-term water consumption dynamics on the island of Bali and in the Moscow region (MR) on the basis of statistic data, reports of management authorities, ministries and institutions. Potential water resources were calculated using the following formula:
PWR = (precipitation – evaporation) × area
Despite the difference in area (the MR is 8 times bigger than Bali) PWR is almost the same. Nevertheless, the PWR structure is different: groundwater constitutes 57% in the MR and 11% in Bali; there is also a considerable difference in precipitation and evaporation due to climate patterns; unlike the MR, Bali has no opportunities for the construction of huge water-storage reservoirs.
In the MR 80% of water is consumed by households and 19% is consumed by industries. Moreover, a considerable amount of domestic water is supplied thanks to groundwater springs which have to be protected from the pollutants by means of sewerage systems (Moscow, the biggest city of the MR, is fully provided with sewerage system). All waste waters are treated and only then go into rivers. On the island of Bali approximately 80% of water is used by agriculture and about 18% is used for domestic needs, which was typical for Moscow in the middle of the XX century. However, nowadays water consumption share in Bali is increasing for domestic and industrial needs, which permits to predict possible consequences as the MR underwent the same changes.
Bali regions with high population density (Denpasar, 6,000 persons per square kilometer) and Moscow (8,000 persons per square kilometer) have similar zones of groundwater deficiency resulted from overconsumption. These zones are being polluted with artificial organic substances such as household chemicals, medicines, petroleum derivatives, and nutrients.
In spite of differences in climate, specific features and water consumption structure, the actual amount of water per 1 person per day in both regions appeared to be the same at that critical moment when the regions started to suffer from water deficiency. This value is about 1m3/1 person/day.
This value is critical and immediate regulating measures should be taken at the government level of both regions – Bali and the MR. These measures can include accumulation of water reserves, separation of drinking water and domestic water, government supervision over water quality, development of treatment technologies, etc.
The proposed measures may change depending on the region under consideration but the identified criterion (critical value of water resources per one person) will help to make a decision in time and avoid unfavorable scenarios which already occur in the water deficiency regions.
LINK to the full text:
I. Nyoman Rai, S. Shobab, N. Shchegolkova, R. Dzhamalov, E. Venitsianov, I. Gusti Ngurah Santosa, Gede Menaka Adnyana, I. Nyoman Sunarta, and I. Ketut Suada. Analysis of the Specifics of Water Resources Management in Regions with Rapidly Growing Population under Different Climate Conditions: Case Study of Bali Island and the Moscow Region / Water Resources, 2015, Vol. 42, No. 5, pp. 735–746.