African Regional Center Foe Echohydrology




Ecohydrology (EH)  nature based solution (NBS) which uses the relationships between hydrological and biological processes from molecular to basin scale by ‘’dual regulation’’ for improvement of water quality, biodiversity and ecosystem services and resilience for society (Zalewski 2000).


Ecohydrology concept developed by UNESCO IHP Programme and International Institute of Polish Academy of Sciences – European Regional Centre for Ecohydrology under the auspices of UNESCO in Poland and Department of Applied Ecology of the University of Lodz in Poland,


The concept is based upon the assumption that sustainable development of water resources is dependent on the ability to restore and maintain evolutionarily established processes of water and nutrient circulation and energy flows at the basin scale.


This depends on an in-depth understanding of a whole range of processes involved that have a two-dimensional character:


Temporal: spanning a time frame from the past to the present with due consideration of future global change scenarios; and


Spatial: understanding the dynamic role of aquatic and terrestrial biota over a range of scales from the molecular- to the basin-scale.


Both dimensions should serve as a reference system for enhancing the buffering capacity of ecosystems against human impacts by using ecosystem properties as a management tool. This, in turn, depends on the development, dissemination, and

implementation of interdisciplinary principles and knowledge based on recent advances in environmental science




Up to the time when the ecohydrology concept was defined, hydrologists considered aquatic biota mostly as an indicative system for monitoring while hydrobiologists considered hydrological processes as a disturbance factor (fig1).



                         (fig 1), Traditional Approach b/n Biologist and Hydrologist



source: Source: European Regional Centre for Ecohydrology UNESCO / Lodz, Poland



The ecohydrology paradigm, which is based on functional relationships between hydrology and biota (Zalewski et al. 1997, Zalewski 2000; 2002), can be expressed in three key assumptions.




REGULATION of hydrology by shaping biota and, vice versa, regulation of biota by altering hydrology (fig 2).


INTEGRATION - at the basin scale various types of regulations (E <-> H) act in a synergistic way to improve and stabilize the quality of water resources.


HARMONIZATION of ecohydrological measures with necessary hydrotechnical solutions (e.g., dams, sewage treatment plants, levees at urbanized areas, etc.)



                                (New Approach b/n Biology and Hydrology,



source: Source: European Regional Centre for Ecohydrology UNESCO / Lodz, Poland


The general assumption of EH is to reverse degradation and achieve sustainable water and ecosystems in anthropogenically modified basins. In addition to the reduction of erosion, nutrients and pollutant emissions there is a necessity to regulate ecological processes based on understanding "water - biota interactions", from molecular (e.g., microbial loop) to ecosystem (biomanipulation) and to landscape scales (reforestation, creation land/water ecotone zones).







1. FRAMEWORK - Integration of the catchment, water and its biota into one entity, including:


Scale - the mesoscale cycle of water circulation within a basin is a template for the quantification of ecological processes;


Dynamics - water and temperature are the driving forces for both terrestrial and freshwater ecosystems; 


Hierarchy of factors - abiotic (e.g., hydrological) processes are dominant in regulating ecosystem functioning. Biotic interactions may manifest themselves when abiotic factors are stable and predictable.


2. TARGET - Understanding evolutionarily established ecohydrological processes is crucial for     

                        a proactive approach to the sustainable management of freshwater resources.


It assumes that it is not enough to simply protect ecosystems but, in the face of increasing global changes (such as increasing population, energy consumption, global climate change), it is necessary to increase the carrying capacity of ecosystems, and their resistance and resilience, to absorb human-induced impacts.


3 METHODOLOGY- ecohydrology uses ecosystem properties as a management tool. It is              applied by using biota to control hydrological processes and, vice versa,   by using hydrology to regulate biota. Scientific basis for the methodological   aspect of using biota  for water quality improvement has been seriously advanced by ecological engineering (e.g., Mitsch  &  Jorgensen, 2004).



The third principle features three steps of implementation which comprises the major body of Ecohydrology (Zalewski 2000)
















Technical approach is not enough


The importance of the effort to develop the ecohydrology approach increased with the publication of the paper by Meybeck (2003) in which he justifies the name of Anthropocene for the present era. Based on an in-depth analysis of published studies, he demonstrated that the modification of aquatic systems by human pressures (e.g., flood regulation, fragmentation, sedimentation imbalance, salinization, contamination, eutrophication, etc.) has increased to a level that no longer can be considered as being controlled by only natural processes (climate, relief, vegetation, limnology), thus defining a new era that we have already entered.


The decline in water quality and biodiversity, observed at the global scale in both developed and developing countries, has provided evidence that the traditional „mechanistic” approach focused on elimination of threats, such as point source pollution and flood control, is crucial but not sufficient. This is because purely technical control, without understanding and considering biotic dynamics, constitutes a more trial and error approach to water management than the imple-mentation of a policy toward sustainable water use. While elements of this approach remain valid and viable, a technical solution alone is clearly insufficient

for the sustainable use of the world’s water resources.


To guarantee the sustainability of freshwater resource use, it is necessary not only to reduce or eliminate the discharge of pollutants, but also to extend the number of potential tools to manage the degradation of ecological processes in landscapes. Such a more efficient approach must be based on an understanding of the temporal and spatial patterns of catchment scale water dynamics



Two halves of ecohydrology can be distinguished:


  1. Atmospheric / terrestrial,

Where the major question is how plant cover changes the  dynamic water balance and nutrient/pollutant transfer in to aquatic ecosystems,


  1. Aquatic,


Where biotic interactions may change nutrient/pollutant allocation from dynamic to non-available pools, such as changing the intensity of eutrophication (by an order of magnitude).



EH goals as a problem-solving science:


(1) Slowing down the transfer of water from the atmosphere to the sea (considering flood

      and drought control as priorities),


(2) Reduce input and regulate the allocation of excess nutrients and pollutants in aquatic

ecosystems to improve water quality, biodiversity and human health,


(3) Enhancement of ecosystem carrying capacity (resilience, biodiversity, ecosystem services for society) in harmonization with the societal needs within the framework of Integrated Water Resources Management (IWRM).


The integration of the dynamics of the three components, catchment, water and biota into a “super organism” determines the management target of Ecohydrology - the maintenance of its homeostatic equilibrium measurable by biodiversity, water quantity and quality and ecosystem services

Fig 4, Application of Ecohydrology in problem solving (Zalewski 2017)




We are aware that in the face of climate change, population pressure and economic development a ‘business-as-usual’ approach to water management neglecting the ecosystems that sustain life and well-being is no more sustainable. The continued deterioration of water ecosystem in terms of its quality, quantity and biodiversity is a clear evidence for the inadequacy of the existing conventional water management. The answer to understand natural processes and apply nature based solution.  

Genesis of Ecohydrology in Ethiopia:

The progressive degradation of water resources and biodiversity is the most important phenomena from the point of view of sustainable development in Ethiopia.  The country faces environmental challenges such as land degradation, limited quantity and quality of water resulting from progressive deforestation, improper agricultural practices, urbanization, over exploitation of natural resources and drainage and cultivation of wetlands which is further exacerbated by demographic and climate change. With the view of reversing these problems, efforts have been made to launch afforestation and conservation programs by governmental and nongovernmental organizations; however, success to date is limited when it comes to the basin scale. The purely technical control of waters, overlooking the dynamics of the biotic component, cannot be considered as a sustainable management approach. MoWIE introduced the new paradigm-Ecohydrology in collaboration with European Regional Center for Ecohydrology (ERCE) located in Lodz-Poland and it has been implemented since 2008.


African Regional Center for Ecohydrology (ARCE)

African Regional Center for Ecohydrology (ARCE) is the water related centers established as category 2 centers under auspices of UNESO on in 2015 during the 38th session of General Conference in Paris.

The center is accountable to the Ministry of Water and Energy of the Democratic Republic of Ethiopia(MoWE) and work on relevant thematic and geographic priorities in their area of expertise. in Reducing anthropogenic impacts on ecosystems through managing dual regulation of hydrology and biota, taking into consideration multi-dimensional parameters at river basins scale : Water, Biodiversity, Ecosystem Services for Society, Resilience to climatic changes and cultural heritage.