Are Dams More Beneficial Than Detrimental To Man?

Water is a critical natural resource. Without it, life could not exist and people could not survive. For more than 5000 years, dams have provided people with reliable sources of water for their survival.

Most dams have a section called a spillway or a weir over which, or through which, water flows either intermittently or continuously, and some have hydroelectric power generating systems installed. A dam- reservoir facility provides numerous benefits including generating electricity, direct water from rivers to canals, and irrigation and water supply systems, increase river depths for navigational purposes, to control water flow during times of flood and droughts, create artificial lakes for fisheries and recreational use, ground water recharge, etc. Many dams are multipurpose and fulfill several of these reasons.

One of the danger dams pose to any environment it is situated is Dam failure. Although comparatively rare, dam failure can cause immense damage and loss of life when they occur.

In 1975, the failure of the Banqiao Reservoir Dam and other dams failure in Henan Province, China caused more casualties than any other dam failure in history. The disaster killed an estimated 170,000 people and 11 million people lost their homes.

Dam destruction is one of the greatest man-made disasters that can instantly generate casualties and will bring about disastrous consequences. Dams and reservoirs in Nigeria are of particular importance in the north of the country, where rainfall is low. The construction of dams of appreciable heights and storage capacity became possible after the development of cement concrete and the mechanization of earth moving and material handling equipment. The last century witnessed a dramatic increase in the construction of large dams. By 1994, about 5000 large dams had been built worldwide, three-quarter of them in industrialized countries. Today, over 45,000 large dam had been built in over 140 countries of the world.

However, many negative effects of large dams especially hydroelectric dams have come to light, slowing the progression of future dams. Throughout the past few years, the negative impacts of dams have become so well known that most countries have stopped building them altogether and are now forced to invest their money into fixing the problems created by existing dams.

The following reasons make the construction of dams a thought-provoking venture:

Impact of Cultural Heritage

Dams have adversely affected the cultural heritage of many communities through loss of cultural resources (temple, shrines, and sacred elements of the landscape, artifacts and buildings). The submergence and degradation of archaeological resources (plants and animals remains, burial sites and archaeological elements are other significant cultural impacts of dams.

Dams can also cause loss of or damage of cultural heritage through land reclamation and irrigation project. During the construction of the Inanda dam in South Africa, remains of human bodies buried under the reservoir site were exhumed and all buried in one hole profoundly disturbing local communities. The risk of submerging ancestral graves is one of the reasons the Himba people in Namibia opposed the planned Epupa dam.

Health Related Impacts
Dam reservoirs in tropical areas, due to their slow-movement, are literally breeding grounds for mosquitoes, snails, and flies, the vectors that carry malaria, schistosomiasis, and river blindness. Numerous vector-borne diseases are associated with reservoir development in tropical areas. Schistosomiasis (or Bilharzias), for instance, spread through snails breeding in still or slow moving waters was a significant public health problem that emerged from many water development projects. Most reservoirs and irrigation projects undertaken in malaria endemic areas increase malaria transmission and disease. The increase was more pronounced for dams below 1900 meters of altitude and less pronounced above that altitude.

Soil Erosion
One of the first problems with dams is the erosion of land. Dams hold back the sediment load normally found in a river flow, depriving the downstream of this. In order to make up for the sediments, the downstream water erodes its channels and banks. This lowering of the riverbed threatens vegetation and river wildlife. A major example of soil erosion problems is the Aswan Dam.

One of the reasons dams are built is to prevent flooding. However, most ecosystems which experience flooding are adapted to this and many animal species depend on the floods for various life-cycle stages, such as reproduction and hatching. Annual floods also deposit nutrients and replenish wetlands.

Species Extinction
As fisheries become an increasingly important source of food supply, more attention is being paid to the harmful effects of dams on many fish and marine mammal populations. The vast majority of large dams do not include proper bypass systems for these animals, interfering with their life cycles and sometimes even forcing species to extinction.

Having pointed out the demerits of having a dam, we cannot rule out the fact that the advantages of dams are immense as stated at the beginning of this piece

Advantages of Dams
1. Clean, efficient, and reliable form of energy.
2. Does not emit any direct pollutants or greenhouse gases.
3. While the initial cost is high, they are very inexpensive to operate.
4. Electricity generated by hydro-electric power plants is the cheapest electricity generated.
5. Dams prevent flood.
6. Dams store water for irrigation in summer seasons and dry months. Many desert areas can now farm due to dams and canals that supply water.
7. Dams supply water for local drinking needs.
8. Allows for fish farming.

In 2012, Nigeria experienced her worst flood disaster since independence. The disaster was worsened by the opening of the Lagdo dam in Northern Cameroon.

There are about 17 dams in Nigeria serving different purposes of irrigation, water supply and hydroelectricity.

So what’s your take? Do you think Dams are more beneficial than they are detrimental?

Read also: Structural failures in Nigeria and its agents