Integrating Ecological Integrating Ecological Approach in Watershed Approach in Watershed

ManagementManagement

About the About the PresentationPresentation

• The objective of this PPT is to explain the significance of ecological approach in present watershed development.

• It starts with discussing the salient features of the present watershed development model and explains the difference in ecological planning and management for the same.

• At the end two management alternatives are presented where detailed explanation of ecological restoration of streams and vegetation cover design is given.

Present Watershed Present Watershed DevelopmentDevelopment

Salient Features

• Watershed and its subsystems

• Core Objectives• Approach• Soil Conservation Measures• Measures for Water Harvesting

in Stream

Typical Understanding of Typical Understanding of Watershed and Its subsystemsWatershed and Its subsystems

Present Point of View for management

• Engineering Structures - Gabion, Gully Plugging, Check Dams

• Area under tree cover- Agro forestry, Horticulture, Silvipasture,

Intensive cultivation

• Non Cultivable Area (wasteland)

• Human Settlement

Ecological Approach: Key Ecological Approach: Key concepts in understanding concepts in understanding

WatershedWatershed • Bio-Geographic zones

• Understanding Mosaic

• Natural Processes

• Natural Services

• Biodiversity

• Microclimatic conditions

Understanding MosaicUnderstanding MosaicLandscape as a Mosaic

The land is always spatially heterogeneous (an uneven, non-random distribution of objects), that always has structure. The key is solar energy. Over geologic time it produces landforms, and today it grows different plants, which provide structure or heterogeneity to the land.

Three mechanisms create Mosaic pattern

Substrate Heterogeneity – hills, wet spots and different soil types, causes vegetation patchiness.

Natural Disturbance – fire, heavy rains, pest explosions etc.

Human Activity – Plowing Fields, cutting woodlots, building roads, creating patches, corridors, boundaries.

Various biological processes commonly modify and enhance the pattern.

Natural ProcessesNatural ProcessesBiogeochemical cyclesThe chemical elements, including all the essential elements of protoplasm, tend to circulate in the biosphere in characteristic paths from environment to organisms and back to the environment. These more or less circular paths are known as biogeochemical cycles.

Nutrient cyclingThe movement of those elements and inorganic compounds that are essential to life can be conveniently designated as nutrient cycling.Example – Nitrogen cycle, Phosphorous cycle, Sulfur cycle etc.

Natural Processes The rate of release of nutrients from the solids, the solar input and the cycle of temperature, day length and other climatic conditions are the most important processes, which daily regulate the rate of function entire ecosystem.

Four Ecosystem processes: Water cycle, Mineral cycle, Energy flow, Community dynamics (also called succession).

Modifying any one of these processes automatically changes all of them because in reality, they are only different aspects of the same thing.

Natural ServicesNatural ServicesNatures services which are essential for human life, are generated by a complex of natural cycles driven by solar energy, that constitute the workings of the biosphere, the thin layer near earth’s surface that contains all known life.

Following are few important natural services

Purification of air & waterMitigation of floods & droughtsDetoxification & decomposition of wastesGeneration & renewal of soil & soil fertilityPollination of crops & natural vegetationControl of vast majority of potential agricultural pestsDispersal of seeds and translocation of nutrientsMaintenance of biodiversity, from which humanity has derived key elements of its agricultural, medicinal & industrial enterpriseMaintaining the global atmosphere, regulating the earth’s weather patterns

Bio-DiversityBio-DiversityIndian BiodiversityIndia covers about 2% the land area of the world but possesses more than 8% of world’s Bio-Diversity. High endemism is the character of the Indian Biodiversity. Hence Biodiversity loss is irreversible.

ImportanceAs explained earlier together with physical conditions, biodiversity also helps to define characters of nature’s services. If an area atmosphere, soil and water are polluted, nature’s services will be affected. The existing biodiversity will be an indicator of disturbed condition.The variety of species provides a gigantic gene bank which becomes an unlimited source of food & fiber, medicines, antibiotics, pesticides and raw materials for different industries.Wild genes are much stronger in resisting diseases and can impart this strength to domesticated plants such as crops to make them pest resistant.

Present Threat :

Ecological knowledge is inadequate

For Biodiversity it is not only the number and variety of species and sub-species of plants and animals, higher and lower but also, includes the variety of habitats & niches available in particular area. Habitat is the address & niches available is the profession of each species.

It is extremely difficult to separate out and count each and every habitat and niche as they are connected to each other & to larger divisions like biomes in a maze of linkages.

Hence conservation of Biodiversity through protection and elimination of human impacts, which means a kind of relapse into conditions that existed sometimes in the past. The same can be called Restoration of natural processes.

Bio-Geographic zonesBio-Geographic zones

• Biogeography

The study of the patterns of distribution of organisms in space and time is called biogeography.

India – A Tropical Country

Characteristics of the

Tropics

1. High Temperature

2. Monsoon

3. Acute Water Shortage

4. Fragile Soils – poor moisture

retention and organic content

5. High Evaporation Rate

6. High Decomposition Rate

Bio-Geographic zones of Maharashtra – A Bio-Geographic zones of Maharashtra – A case studycase study

I Konkan – Narrow strip between Arabian Sea and Western Ghats (Sahyadri),

II Crestline of Western Ghats (Sahyadri),

III Slopes,

IV Dry Deciduous Zone of Marathwada and Khandesh,

V Dry evergreen Zone of Vidarbha

Microclimatic conditionsMicroclimatic conditions Microclimates

Areas of natural vegetation, such as forests or grasslands, have distinctive climate, which is a modification of the general climate typical of the geographical region in which they are situated. These modifications are the result both of small-scale geographical variation in terrain—slope, aspect, etc. – and of the shading and deflection of wind and rain by the community itself. Such local climates are called Microclimates.

Important factors in development of Microclimates are the extent of penetration into the vegetation of sunlight energy, of heat, and of wind and rain (which cause cooling and control humidity).

Few illustrations

South facing slopes in Northern Hemisphere receive more sun than north facing ones, for instance, and thus are warmer and tend to be drier. They are also often more sheltered from the cold North-East winds, and these factors influence the biotic community that develops on them.

The vegetation itself greatly influences the climate and community. Tall plants, for instance, provide smaller members of the community with shade and protection from wind and rain.

The Microclimate of grassland is very much influenced by the height and density of the vegetation. When the height of the vegetation varies in different seasons, the microhabitats will also vary. The activities of herbivorous insects such as caterpillars, grasshoppers are very much influenced by the conditions of humidity and temperature among the grasses on which they feed.

Core Objectives in Present Core Objectives in Present ManagementManagement

Soil Conservation

Water Conservation

Present point of view - Ridge Present point of view - Ridge to Valleyto Valley

• Protect the upper reaches to

avoid erosion and reduce runoff

• Avoid siltation of structures in the

middle and lower catchments

• Ensure the cost effectiveness of

structures in the valley

• Improve over all efficiency of

measures

Soil ConservationSoil Conservation

Present Measures

Continuous Contour

TrenchesTrenches

Staggered Contour

Trenches

Continuous Contour

Benches

Contour Farming

Present Objectives

Reduce Soil erosion

Provide vegetation cover

Trenches on slopes will accelerate erosionTrenches on slopes will accelerate erosion

sources from internet

Soil Conservation- Ecological Soil Conservation- Ecological Point of ViewPoint of View

Every landscape has variety of

vegetation cover spread all

over the landscape through

variety of land features right

from upper reaches to bottom

of any slope for example some

where depressions, some

where steep and medium

slopes, rocky out crops etc.

These cover types have a

specific character and role to

play with that land feature for

example reducing erosion,

absorbing rain shocks etc..

Shola Forests in ravines

Cover Type Management- a Missing Cover Type Management- a Missing ComponentComponent

Objectives

Maintain an association between different land

features and their vegetation cover over the landscape, so

as to maintain the biological and physical processes (erosion etc.)

over the landscape.

Significance

Contour trenches or benches as a generalized and

uniform approach all over the slopes from top to bottom is

ecologically incorrect and consideration of physical as

well as biological processes according to land classes is

important

Ecological Point of View – Ecological Point of View – Ridge to Valley through Ridge to Valley through Stream and Cover TypesStream and Cover Types

Stream plays an important role of connection between Ridge and

Valley.

Stream processes that create habitats, integrate the physical and

biological processes across watershed.

Cover types over different land classes plays important role in

maintaining physical and biological processes.

Stream RestorationStream RestorationBefore studying measures lets study

Stream as an Ecosystem

Ecosystem

Every ecosystem has structures and functions, if the balance between them is maintained we get services from it. Any change in structures or functions hampers the balance and hence the services.

Meander, Pools, Riparian Vegetation, Medium size boulders, Medium size channel – Stream in Middle reaches

Structures of Stream Ecosystem

Steps in upper reaches,Pools in all reaches,Riffles in middle and lower

reaches,Meanders in plains, Point Bars in stream channel,Banks on both sides,Floodplains,

Components of Stream

Ecosystem

Watershed,

Riparian Vegetation,

Stream Channel

Functions or Processes of Stream Ecosystem

Transportation of water from land towards sea,

Transportation of sediment load from land towards sea

Services from Stream Ecosystem

Purification of water,

Ground water recharge,

Rich soil in floodplains,

Habitats and Corridors for aquatic as well as other fauna

Dynamic Equilibrium of Dynamic Equilibrium of StreamStream

Stable Stream

A naturally stable stream channel maintains its dimension, pattern and profile such that the stream does not degrade or aggrades i.e. maintains its structures and functions.

Stable streams migrate across the landscape slowly over geologic time while maintaining their form and function.

Naturally stable streams must be able to transport the sediment load supplied by the watershed.

This stable state is called Dynamic Equilibrium of Stream.

sources from internet

sources from internet

Stream InstabilityStream Instability

Unstable Stream

Instability occurs when scouring causes the channel bed to erode (degrade) or excessive deposition causes the channel bed to rise (aggrade).

The product of sediment load and sediment size is proportional to the product of stream slope and discharge—or stream power.

A change in any one of these variables causes a rapid physical adjustment in the stream channel i.e. Stream Instability.Stream Instability causes stream to adjust towards new equilibrium state.

This transition may take long time and cause big changes in water quality, habitat and adjacent property i.e. Stream Services.

Water Harvesting in Water Harvesting in Streams Conventional Streams Conventional

ApproachApproach Present ObjectivesReduce velocity of flowInfiltration of water in soil

Present MeasuresBrushwood checkdamGully plugGabion structureMasonary checkdamRCC checkdamEarthen checkdamUnderground Bandhara

Ill effectsReduction in stream velocity results into stream instability, hence hampering the services.

Permanent Dam obstructing the stream flow, Instream cultivation and Loss of riparian vegetation

Ecological ObjectiveEcological Objective

Stream RestorationStream Restoration

What is Stream Restoration?

Stream restoration is the re-re-establishmentestablishment of the general structure, functions and self-sustaining behavior of the stream system that existed prior to disturbance.

It is a holistic processholistic process that requires an understanding of all physical and biological components of the stream system and its watershed.

Temporary Half moon shaped pool where flow is retained for a while

Restoration includes a broad range of measures, including the removal of the watershed disturbances that are causing stream instability; installation of structures and planting of vegetation to protect streambanks and provide habitat; and then reshaping or replacement of unstable stream reaches into appropriately designed functional streams and associated floodplains.

Ecological MeasuresEcological MeasuresMethodology

Ecological Surveys, Restoration Measures and Monitoring in three important areas of stream ecosystem i.e. watershed, stream channel and riparian vegetation.

Ecological Surveys

Surveys are carried out to understand present conditions of stream (stable or unstable) by assessing physical and biological components of stream in above mentioned areas.

Riparian Vegetation in good condition on one bank and disturbed on other bank

Survey of Riparian Vegetation

A survey of riparian vegetation is carried out to study condition of present vegetation over there, its association with the aquatic as well as terrestrial fauna over there. For example it can serve as a breeding habitat, feeding habitat or corridors for all types of faunas etc.

Survey in Watershed

Study of variety of vegetation cover spread all over the watershed, through variety of land features right from upper reaches to bottom of any slope, some where depressions, some where steep and medium slopes, rocky out crops, wetlands etc.

Survey of Stream Channel

This survey is done in three reaches particularly upper (high slope), middle (medium slope), lower (plains) Highly Eroded Stream Banks

Purpose:To assess condition of Stream banks, check whether erosion is taking place and if yes at what rate.

To assess condition of stream channel, check whether degradation or aggradations is taking place.

To assess human Interferences on stream channel like dams, instream cultivation, degradation or aggradations, use of stream as for waste disposal, pathways for livestock etc.

Restoration MeasuresRestoration MeasuresIn Watershed

Natural Cover Type Management,Maintaining Enclosures or protected areasIdentifying anchoring places and introducing native speciesCreating and Maintaining Natural Cover Type over Gullies and Ravines, which plays important role of moisture retention and corridors for fauna.Live Hedges

Building Half Moon Shaped Pools

In Stream Channel

For Bank and Channel Protection from erosion: Root wads, Rock Vanes (Single, Cross, J-shaped vanes), Point Bars, Rip-Rap etc.

For Habitats creation and Pathways for aquatic fauna: Half moon shaped pools, fish ladders.

Restoration Restoration MeasuresMeasures

In Riparian Vegetation

Protection from cutting and grazing,

Plantation of suitable riparian tree species decided from the survey, in areas where stream banks have lost their riparian vegetation,

Stream banks where riparian vegetation is lost and sever erosion has taken place, initially plantation of grasses is required and later on plantation of trees,

Ecological MonitoringEcological MonitoringA naturally stable stream channel maintains its dimension, pattern and profile such that the stream does not degrade or aggrades.

Following are the methods used for measuring dimensions, pattern and profile of stream channel

Stream Cross Sectional Profile,Pebble count,Pool to Pool distances, Riffle to Pool distances, Riffle to Riffle distances,

Over the years changes in these measurements helps in deciding whether the stream is heading toward stability or instability and whether any changes are required in measures taken. Cross Section of Stream

Forest Cover Design for Forest Cover Design for WatershedWatershed

Before starting the forest cover design lets have a quick look at Ecological groups of Plants

Hydrophytes – Water loving plants

Mesophytes – Normal plants - Evergreen, Deciduous forests.

Xerophytes – Drought escaping - ephemeralsDrought resisting - succulentsDrought enduring - hardy, spiny, thorny.

Halophytes – Waterlogged conditions

Forest Cover Design for Forest Cover Design for WatershedWatershed

Every watershed is composed of various land forms or features from ridge to valley through stream.

We can divide watershed into two areas, Elevated Areas and Plain Areas where we get different land features.

For Elevated Areas following are the land features

Hills,Uplands,Slopes,Wetlands,Rocky Outcrops,Gullies and Ravines,Stream Channels,Difficult Areas

Pioneer Plants on Rubble Heap

Forest on slopes

Forest Cover Design for Forest Cover Design for WatershedWatershed

For Plain Areas following are the land features

Hill base areas and pediments,Flood plain area,Wetlands,Grasslands,Stream course and river basin,

Forest Cover Design

An association between these land features and naturally occurring flora, resulting into relative fauna over there can be called as forest cover design.

Significance of forest cover is that they play important role in keeping both the physical and biological processes over landscape intact.

Grassland

Forest Cover Design for Forest Cover Design for WatershedWatershed

Trees –Trees – Wind movement, Rains, cooling structuresTall Trees obstruct the wind movement which results into lesser evaporation loss of nearby water bodies. Tall Trees are also responsible for rains.Presence of good Riparian vegetation results into cooling of water in stream reducing evaporation loss. In Dry season leaf litter of these trees fallen into the stream channel also results into reducing the evaporation loss through soil.

Riparian Vegetation

Few Cover Types and their Ecological roles

ShrubsShrubs – – Faunal diversity Insects Shrubs provide habitats for lesser fauna like insects etc.

ClustersClusters – Gene bankClusters as an association of shrubs, herbs, tall trees, climbers

serve as a gene bank over any landscape.

Forest Cover Design for Forest Cover Design for WatershedWatershed

Example of cover types in Semi arid regions and their ecological successions

For Ridge top and slopes

Dry deciduous type of forest as the climax ecosystem composition- Hardwickia - Terminalia – Ixora - MiliusaSecondary regeneration - Launnea – Boswellia - AnogeissusThird degree of degradation Acacia - Zizyphus - Thorny speciesFourth degree - Scrub Gymnosporia - Amonii - CissusLastly grasses like Heteropogon - Aristida

For Riparian

Climax compostion Pongam- Jamum – Bauhinia semla Degradation Terminalia Arjuna - Pongam – Madhuca indica Second degree of degradation Fluggea - Ehretia

Forest Cover Design for Forest Cover Design for WatershedWatershed

Example Forest Design for Ridge top

Objective: To convert ridge top into a dry deciduous forest cover

Methodology:

Survey To study present diversity and its distribution and connections,To study variety of land features, difficult areas and their connections, Clusters of grasses, shrubs and trees

Measures in briefCreating “Sponge effect” - Together with well stocked grassland, soil

and ground cover improvements Selection of native plant species according to the land features

available, Creating clusters of combination of shrubs, climbers, tall tress, Creating vegetative connections between these clusters,Grasses in open spaces,Protection to special habitatsFencing – with Dry and Live hedges,

Artificial Plantation Vs landscape Artificial Plantation Vs landscape Mosaic with Natural Cover TypesMosaic with Natural Cover Types

Native VS Non nativesNative VS Non natives

Non natives are not suitable for native ecosystems and

natural processes.

They are not natural habitats for our wildlife.

As there is no natural enemy they grow faster and spread

like a weed.

Gliricidia Gliricidia sp.sp.

Commonly planted non-native Commonly planted non-native speciesspecies

Eucalyptus sp.Eucalyptus sp.

Austrailian AcaciaAustrailian Acacia

Thank Thank You!You!