Towards an ecological assessment of watercourses

Abstract

Due to a fast decline in the ecological quality of watercourses combined with the threat of human functions, policy makers started to legislate water quality objectives for watercourses and to set up water purification programs. The description of universal quality objectives is too limited as a frame of reference and a policy only based on water quality cannot guarantee the goals of river restoration as a whole. In most countries the need for a more integrated approach of water management is growing. Water quantity must be managed together with water quality, surface water with groundwater, and the water economy with town and country planning.To restore and maintain the natural diversity of watercourses, together with the natural species richness, policy makers need a frame of reference based on the natural functioning of the ecosystem. The highest level of reference is called the 'ecological naturalness'. Based on the present and the potential ecological value and on the intensity of human uses, policy makers together with a group of scientists should decide on the ecological quality objectives of watercourses. The lowest quality level that must be reached in all watercourses can be described as the 'ecological basic quality'. Together with a frame of reference, there is a need for a refined ecological evaluation method for ecological quality as a whole, and especially to evaluate 'potential ecological values' in an objective way.

Benchmarking habitat quality: observations using River Habitat Survey on near‐natural streams and rivers in northern and western Europe

“…This might have been because the presence of features rather than number of features was used in the analyses and also an insufficient sample size in certain width categories. Other factors, such as the influence of hydrological regime would also be important to consider, because stable, groundwater-fed rivers generally have far fewer flow-types and in-channel habitat features than active spate rivers of similar gradient and size (Sear et al, 1999;Clifford et al, 2006). Table 4 summarizes the occurrence of features in those rivers where consecutive RHS surveys were carried out (n 5 93 pairs; Appendix 1).…”

Biodiversity, ecohydrology, threat status and conservation priority of the freshwater fishes of river Gomti, a tributary of river Ganga (India)

“…Many countries are now more effectively controlling water pollution, but improvements in aquatic communities are being restricted by habitat deficiencies in river channels and floodplains (Aarts et al 2004). Fish appear to be good indicators of the status of aquatic communities and river environments (Schneiders et al 1993), and fish are often a key element in environmental planning (Schiemer 2000). Conservation areas, management zones, and sanctuaries need to be defined soon, yet knowledge of the ecological requirements of large river species is poor (Hoggarth et al 1996a).…”

A Concept of Integrated Water Management Illustrated for Flanders (Belgium)

“…In order to reach the goals of sustainable de-velopment and ecosystem health, attention needs to be given to biodiversity. All water systems should reach at least a basic or minimal quality level, no matter how high the intensity of human use (Anonymous 1997;Schneiders et al 1993Schneiders et al , 1996. A minimal quality level should permit long-term multifunctional use, avoiding depletion of the water resources and taking into account the necessity of sustaining self-purification capacity.…”

“…A minimal quality level should permit long-term multifunctional use, avoiding depletion of the water resources and taking into account the necessity of sustaining self-purification capacity. In a watercourse reaching basic or minimal quality from a biological point of view, common species should have the possibility to fulfill their whole life cycle and rare or vulnerable species should have the possibility to migrate through the system to feeding or spawning grounds (Schneiders et al 1993). Pristine sites need to be protected for future generations and here the "stand-still principle" for natural water systems applies.…”