1. Conserving freshwater aquatic ecosystems requires consideration of 1
Conserving freshwater aquatic ecosystems requires consideration of 1. Flow regime 2. Water quality Land cover in a catchment affects both

2. Impacts of land-use on hydrological processes
Water Cycle
Human Impacts on Water Resources

4. Watershed land use has overarching effect on the water budget

5. Effect of land use
Activities like clear-cut deforestation- eroded sediments, flooding downstream
Poor agricultural land management activities - eutrophication and possible fish kills.

6. Land use Land cover: Forest
Land use: Teak Plantation, Pine plantation, Protected Forest

7. Land use map

8. Land use and hydrological processes

9. Stage of succession, agriculture
Vegetation type affects infiltration and evapotranspiration
Veg type: Grasslands, forests, single species plantations, mixed species plantations,
Stage of succession, agriculture

12. Red: Deforestation in Shillong area 2000-2012

13. Residential and urban influences on hydrological processes

15. Components of hydrological cycle
Precipitation
- rain, snow, fog interception
Runoff
Storage
Subsurface flow
Evaporation
- soil, plants, water surface

16. P = Precipitation. S = Storage. ET = Evapotranspiration
P = Precipitation S = Storage ET = Evapotranspiration R = Runoff(Discharge)
P + (∆S) = ET + R

17. Stream flow is a function of precipitation
P + (∆S) = ET + R

18. Plantations and afforestation in dry areas leads to decline in annual stream flows, due to losses from ET
P + (∆S) = ET + R

19. P + ∆S = ET + R--------greater Forest
However when baseflow is compared across watersheds, watersheds with greater forest cover have greater baseflow than deforested watersheds
P + ∆S = ET + R greater Forest
P + ∆s = ET + R lower forest
Baseflow: flow in streams when there is no rain, like in the dry season

21. Groundwater flows underground until the water table intersects the land surface and the flowing water becomes surface water in the form of springs, streams/rivers, lakes and wetlands.
Baseflow is the continual contribution of groundwater to rivers and is important source of flow between rainstorms. Groundwater continues to discharge as baseflow because of the new recharge of rainwater in the landscape.

23. Now, droughts in the world’s wettest place,
Cherrapunjee, Khasi Hills, Meghalaya, India

26. Dry season – by Jan and Feb – springs are drying up.
People carry water up and down hills for long distances.
Causes:
Deforestation
-- rainwater runs off
-- soil washed off
-- less soil to hold water
-- soil compaction and
hardening due to
exposure to sun and wind
Climate change
Population increase
-- cement industry using
limestone

27. Cherrapunjee High Rainfall & Rainfall intensity
Low Infiltration, due to armoured substrate, lack of vegetation
High Discharge/runoff, as a result of high slope
P + ∆S = ET + R

29. Soil erosion through deforestation:
Madagascar

30. Many aquatic macroinvertebrates
Live in gaps between and under stones
Pristine streambottom – lots of gaps
Sediment choking gaps between stones

31. Trees protect fishes

32. Riparian vegetation buffers
Buffer Width depends on the amount of sediment in runoff:
a function of
Slope,
rainfall,
soil type
land cover (whether primary forest, plantation, agriculture, lack of terraces, urban)

33. 30 m buffer width for rivers in Tanzania

34. Rice field terraces on hillslopes in Yangshuo, China

35. Fluvial geomorphology, stream restoration
Channelized streams for flood control, irrigation, development
Negatives – loss of aquatic ecosystem habitat. Changes in flow regimes,
Los of streambank stability, increased erosion, flooding and breaching
So stream restoration, needs fluvial geomorphology knowledge.

36. A natural stream: diverse morphology and habitats

37. Stream orders in a watershed

39. Steep slopes in headwater catchments

41. Lower elevations,
Lower slopes

42. Streambanks and Floodplains: dynamic

43. The end of the road.. Or stream

44. About two-thirds of the world’s population depends upon groundwater

45. Groundwater resources
Better quality usually than surface water,
In terms of bacteria, sediments and
chemicals in developing countries.
Increasing use in rural communities via
Tube wells
Heavy use in irrigation and urban water supply
Increasing use in bottled water too.

46. Groundwater terminology

47. Aquifer capacity
Sand/limestone
Silt/loam/clay

48. Groundwater movement – slow

49. Unsustainable: Groundwater resources - issues Extraction GREATER THAN
natural GW recharge
Falling water table -> wells run dry
Deep GW extraction can mobilize arsenic (toxic)
GW quality deteriorating from leaching
Forests and wetlands degrade due to lowered water table
Land subsidence (eg Mexico City, Bangkok, Venice)
Salt water intrusion into aquifer (Hallandale, Miami)

50. Groundwater overextraction
Nearly a third of India is suffering from chronic water shortages,
and making up for it with "the world's largest groundwater mining operation“
--National Geographic special report on global water issues, 2010.

51. Seawater intrusion

52. Questions and discussion…