Lecture 1 Integrated water resources management and wetlands

Transcription

1 Wetlands and Poverty Reduction Project (WPRP) Training module on Wetlands and Water Resources Management Lecture 1 Integrated water resources management and wetlands 1

2 Water resources and use The hydrological cycle describes the flows of water on the planet between oceans, land and atmosphere condensation precipitation snow pack evaporation ocean stream flow transpiration evaporation and transpiration wetland storage stream flow snowmelt and surface runoff infiltration groundwater movement to streams, lakes, wetlands and the ocean water table 2

3 Water resources and use Distribution of world s water resources Volume (mill.km 3 ) % of total Exchange rate (y) Oceans Groundwater Ice sheets and glaciers Surface water on land Soil moisture Rivers Atmosphere (vapour)

4 Water resources and use Per capita urban water consumption Europe North America : liters per day (high : ) developing countries : liters per day (low : 10-40) Use versus consumption After consumption no longer available for further use Non-consumptive use: water can still be used by others examples : fishing, navigation Use is greater than consumption because of inefficiencies e.g. return flows from agriculture 20-40% 4

5 Water resources and use Water use by sector: agriculture, industry, municipal, reservoirs Agriculture uses 66% of total withdrawal 5

6 Water resources and use Water use by region: Asia, N-America, Europe, Africa, S-America, Australia 6

7 Water resources and use Water use by sectors: Northern Europe versus East Africa 7

8 Water resources and use Traditional approach in water management by sectors agriculture industry municipal (drinking water and sanitation) But: environment also needs water Water is scarce resource, efficient management is needed Water for nature should be considered because nature needs to be conserved because degradation of nature has negative consequences for society (income, food, health, well-being) Environmental flows or Environmental water allocation is new branch of aquatic science 8

9 Water resources and use Environmental flows/water allocation the quality, quantity and distribution of water required to maintain the components, functions and processes of aquatic ecosystems on which people depend deals with finding balance between use of water and protection of water and environmental resources stakeholders are involved in setting objectives 9

10 Introduction to IWRM Traditional approach for water management Sectoral division: Irrigation Water supply Sanitation (blue water) Top-down approach Supply management (there is enough water, problem is how to transport, process and deliver it, engineering problem) Water managers are not primarily interested in environment/wetlands New, integrated approach for water management Holistic approach (all water types and uses, all sectors) Involves stakeholders Demand management (water is scarce, use should be as efficient as possible, management problem) Water management is linked to environmental management 10

11 Introduction to IWRM Water stress wasteful collection methods high consumption pollution of the ground and surface waters 11

12 Introduction to IWRM The Dublin Principles (International Conference on Water and the Environment 1992) 1. As fresh water sustains life, development and the environment, a holistic approach to water management is needed, linking social and economic development with the protection of natural ecosystems. 2. Water management should be based on a participatory approach. 3. Women take a central role in the provision and management of water. 4. Water should be considered an economic good, but people should have access to clean water and sanitation at an affordable price. 12

13 Introduction to IWRM Definition IWRM is the management of surface and sub-surface water in qualitative, quantitative and environmental sense from a multi-disciplinary and participatory perspective and focused on the needs and requirements of the society at large with regard to water for now and in the future (aiming at sustainability) IWRM is concerned with all water resources Surface water (rivers, lakes, wetlands, springs, pans, sea, delta, coastal zones, mangroves, etc.) Groundwater Green water Atmospheric water Wastewater 13

14 Introduction to IWRM IWRM has the following components: addresses all natural aspects of water + linkages (quantitative, qualitative, ecology) puts water management in broader economic development and environmental context takes account of sector interests with stakeholder participation considers spatial and temporal variation of supply and demand considers all policy objectives and constraints takes into account institutional aspects of water management Scale River basins are the appropriate scale for IWRM 14

15 Introduction to IWRM IWRM deals with all components of the environment condensation evaporation stream flow transpiration evaporation and transpiration wetland storage precipitation stream flow snowmelt and surface runoff infiltration groundwater movement to streams, lakes, wetlands and the ocean snow pack water table ocean 15

16 Introduction to IWRM Atmospheric, marine, aquatic, terrestrial and sub-terranean components Ecological processes regulate the hydrological cycle condensation evaporation stream flow marine: liquid ocean transpiration evaporation and transpiration aquatic: liquid wetland storage atmospheric: vapour, liquid, solid precipitation stream flow snowmelt and surface runoff infiltration groundwater movement to streams, lakes, wetlands and the ocean sub-terranean: liquid snow pack terrestrial: liquid water table 16

17 Introduction to IWRM 17

18 Introduction to IWRM Blue and green water Globally, 40% of all rainfall becomes surface and sub/surface runoff. This is blue water 60% of all rainfall return to atmosphere as evaporation or is taken up by vegetation. Latter part is green water World food production: 60% green, 40% blue Blue water: no scope for expansion, therefore need to use green water Using technology to make freshwater Fog harvesting Desalination 18

19 Introduction to IWRM Trigger for action Social and economic development Supply oriented measures River basin water resources Water supply Water demand Water users Demand oriented measures River basin ecosystem Trigger for action 19

20 Importance of wetlands for water resources Wetlands are everywhere in the river basin headwaters floodplains coastal No wetlands, no water most water from surface and groundwater, quality and quantity depend on wetlands High Altitude Crater Lake Mudflats Lowland River Upper Course of River Ox-bow Lake Reef Flats/Seagrass Beds Irrigation Scheme Coral Reef Drop Off Open Sea Wetlands within river basin High Altitude Stream Man-made Lake (Reservoir) Middle Course of River Mangroves Limit for Definition 20

21 Importance of wetlands for water resources Wetlands perform essential functions and services A wetland function is the capacity of the wetland to provide goods and services Services are the benefits that humans derive from the functions Wetland ecosystems: components components (water, (water, soil, soil, vegetation, vegetation, fauna) fauna) processes(primary processes(primary production, production, decomposition, decomposition, etc.) etc.) functions functions (hydrological, (hydrological, water water quality, quality, etc.) etc.) Services for for humans, e.g. e.g. goods goods (water, (water, fish, fish, etc.) etc.) protection protection from from floods floods purification purification of of wastewater wastewater etc. etc. 21

22 Importance of wetlands for water resources Hydrology and hydraulics Biodiversity Climatic effects Natural functions of wetlands Habitat Water quality 22

23 Importance of wetlands for water resources Hydrological and hydraulic functions Flood control Coastal erosion protection Sediment retention Groundwater recharge/discharge Water holding capacity Stream and river flow 23

24 Importance of wetlands for water resources Hydrological and hydraulic functions The majority of wetlands significantly influences one or more components of the water cycle Most floodplain wetlands in the world reduce or delay floods. For headwater wetlands, this is less clear Substantial number of wetlands in headwaters increase flood peaks Majority of wetlands increase evaporation and decrease average river flow, especially during dry periods In floodplains, wetlands generally reduce flood peaks Many wetlands exist because they overlie impermeable layers of soil or rock Review of 169 studies (Bullock and Acreman, 2003) 24

25 Importance of wetlands for water resources Hydrological and hydraulic functions Evapotranspiration recycles moisture. Globally, 61% of precipitation on land stems from evapotranspiration from land. In arid regions (e.g., the Sahel, Niger basin) 90% of rainfall can come from evapotranspiration Reduction in vegetation cover or in diversity of vegetation reduces evapotranspiration and therefore rainfall Cultivated areas generally have lower evapotranspiration and higher runoff than natural areas because of lower plant density and lower biodiversity Some crops evaporate more than others. Rain forests and swamps have higher PET than evaporation from open water. Papyrus and water hyacinths can evaporate 2-4 times the open water evaporation 25

26 Importance of wetlands for water resources Climatic effects of wetlands Global warming amelioration by carbon fixation and CO 2 balance The hydrological cycle (role in evapotranspiration; see previous slide) Micro-climate stabilisation CO 2 CO 2 CO 2 CO 2 Carbon stored in vegetation and sediments Destruction of wetlands can lead to increases in atmospheric carbon (CO2) which can contribute to global warming (greenhouse effect) 26

27 Importance of wetlands for water resources Water quality functions Filtration of particulates Nutrient stripping Biodegradation of toxic compounds Heavy metal stripping and accumulation Wastewater treatment 27

28 Importance of wetlands for water resources Habitat functions Wildlife habitats Fish feeding and breeding grounds Bird feeding and breeding grounds Terrestrial / aquatic habitats Protects biodiversity and gene pools 28

29 Importance of wetlands for water resources Biodiversity functions Species and population diversity Link between terrestrial and aquatic ecosystems Microbiological activity Large genetic pool Wetlands as connectors 29

30 Importance of wetlands for water resources Biodiversity functions Wetlands as connectors Flyways and biogeographical islands (global north-south) River corridors (upstream-downstream) Longitudinal connectivity with estuarine and marine environments (ocean-land) Wetland ecotones (dry-wet) Connectivity with global systems carbon, nitrogen and water cycles Connectivity with groundwater (aboveground-belowground) 30

31 Importance of water for wetlands Environmental water allocations to wetlands Definition The water quantity and water quality required to maintain a particular ecological character of the water resource which will sustain selected wetland ecosystem functions and services Concepts Many wetlands already modified, so complete restoration is not possible Environmental flows should support a level of ecological integrity that secures the services and benefits of wetlands Environmental allocation competes with other water uses: drinking water, sanitation, food security 31

32 Importance of water for wetlands Objectives of water allocation to wetlands Objectives should be set by stakeholders Objectives should take into account linkages of wetland with the catchment (upstream-downstream) Objectives include environmental, risk-based and socio-economic objectives Environmental objectives: water quantity, quality, habitat integrity (physical and vegetation), biotic integrity (community structure and diversity) Risk-based objectives: minimum flow should not be determined by flooding risk only, but also by ecological importance and sensitivity Socio-economic objectives: extent to which people depend on the wetland for other water uses (agriculture, aquaculture, recreation, etc.) and income/jobs 32

33 Importance of water for wetlands Management of environmental flows for wetlands Supply-side management When water flows are already regulated (dams or other flow control structures), operating rules can be used for water allocation to wetlands Requires technology and management to work well Demand-side management Focuses on regulating upstream demands and land use practices to ensure adequate flows to wetlands Requires changes in agricultural and other practices Demand management should be done at three levels: catchment level (balance water needs of different sectors/users) sector level (ensure efficient water use) end-user level (ensure efficient water use and prevent wastage) 33