Aquatic ecosystem services of reservoirs in semi-arid areas: sustainability and reservoir management

Abstract

The multiple use of reservoirs is widely accepted, but there are frequent conflicts between water users based on ecological, economic and sociological concerns. The promotion of aquatic ecosystem services is a successful approach to advanced reservoir management. The main aquatic ecosystem services are goods and human benefits such as clean water and hydropower. The sustainability of aquatic ecosystem services must be the aim of a reservoir management plan, and hence adequate water quality and predominantly mesotrophic conditions are necessary. However, eutrophication processes are advanced in many tropical reservoirs, and re-oligotrophication is needed, as has been successfully implemented in temperate lakes. The eutrophication processes and re-oligotrophication potential of tropical reservoirs are significantly different from temperate ecosystems. Studies to quantify the impact of ecosystem services were conducted on the Itaparica reservoir, São Francisco River, Brazil, which is located in a semi-arid area. The main disturbance to tropical reservoirs is the change in water level due to hydropower operational conditions. Desiccated areas on the lakeshore have a high potential for nutrient release by sediment mineralization. An increase in the water level promotes the growth of some pioneer plants, such as the water pest, Egeria densa. Intensive net cage aquaculture can lead to an overcharge of the reservoir, and therefore the carrying capacity should be considered. Furthermore, sediment management and the abstraction and re-use for soil amendment has to be managed. The multiple water uses and sustainability of aquatic ecosystem services must be the aim of any reservoir management plan, and the eutrophic level is a key factor due to its impact on water quality.

Review: Water quality in non-perennial rivers (with erratum)

“…An important point to note is that N-PRs are usually found in arid areas where ambient air temperatures are relatively high. As a consequence, evaporation rates are also elevated, increasing the salinity of standing water and damp soils Gunkel et al, 2015).…”

“…In a similar way to rivers, the banks of reservoirs in semi-arid areas undergo desiccation during dry periods. Organic material on the banks becomes mineralized and after re-wetting N, P and C are dissolved into the water and released from the detritus (Gunkel et al, 2015). Thus, when flow resumes in the river, the concentrations of solutes and loads of suspended solids at the edge of the advancing front can be very high, and can exceed base flow concentrations by orders of magnitude.…”

Estimation of benefits from the actual use of inland water ecosystem services in the Slovak Republic

“…The riverbed sediments resulting from the surface water purification process are generally recommended to be used for the improvement of soil properties (Gunkel et al, 2015). Their practical use is limited because the content of pollutants that are bound to the organic or inorganic fraction of these sediments usually prevents their application to agricultural land.…”

Fisheries or aquaculture? Unravelling key determinants of livelihoods in the Brazilian semi-arid region

“…In the latter, reservoirs created primarily for drinking water and for agriculture and animal husbandry are also used for cage aquaculture, especially for the exotic Nile Tilapia ( Oreochromis niloticus Linnaeus). Tilapia cage aquaculture has been presented as an important alternative and is supported by state and federal governments as a means of improving poverty indexes and food security levels in this Brazilian region, which is marked by low social development indexes and by harsh environmental conditions (Gunkel, Lima, Selge, Sobral & Calado, ; Sampaio & Batista, ). However, reservoirs have historically been used for fisheries, which depend on previously stocked native and exotic species (Attayde, Brasil & Menescal, ).…”