Results & Discussion
Status and transitions of forests: This is
evaluated through the assessment of land use dynamics and
fragmentation of forest landscapes using the temporal remote
sensing data of 1973 and 2018. Land use dynamics with the
fragmentation of forests across five major river catchments
of Uttara Kannada district in Central Western Ghats are
presented in Figure 3 and statistics are presented river
basin wise in Figure 4. Land use analyses using temporal
remote sensing data reveals that the overall forest cover in
the district has declined from 74.19% (1973) to 48.04%
(2018), with the loss of evergreen forests from 56.07% to
24.85%. The loss of forest cover is due to developmental
activities with the aggravated anthropogenic activities94
such as i) construction of dams along river Kali post 1975
without appropriate rehabilitation and catchment restoration
measures, ii) increase in monoculture plantations such as
teak, eucalyptus, acacia by the forest department as part of
social forestry scheme, iii) conversion of area under
forests to agriculture, horticulture or private
plantations82,95, iv) increase in built up area,
v) setting up of forest based industries, vi) nuclear power
plant at Kaiga in the midst of evergreen
forests75, etc.
Figure 4. Land use and forest fragmentation dynamics.
Fragmentation process involves alteration in the structure
and composition of native forests through the division of
contiguous forest into smaller non-contiguous fragments with
a sharp increase in edges. This will have detrimental
effects such as disruption in bio-geo chemical cycling,
nutrient and water cycling, ecological processes, easier
access and further land use changes. About 64,355
Ha of forest land has been diverted for various non-forestry
activities (such as paper industries, hydro-electric and
nuclear power projects and commercial plantations) during
the last four decades by the government75. Due to
these, the terrestrial forest ecosystems in Uttara Kannada
district, Central Western Ghats have been experiencing
fragmentation of contiguous forests, evident from the
decline of interior or contiguous forests from 62.71% (in
1970) to 24.74% (2018) and consequent increase in patch,
transitional, edge and perforated forests. This has led to
the loss of connectivity natural/native vegetation and wild
animals straying into human habitations. Instances of
human-animal conflicts, has increased. There is also
extirpation of gene due to higher inbreeding, loss of
biodiversity, absence of native pollinators etc. Spurt in
urban growth is witnessed in and around major towns such as
Sirsi, Siddapura, Karwar, Hubli, Ankola, Kumta, Honavar,
Dandeli, etc. Encroachments of forest lands of the order of
7072 Ha75 and conversion to agriculture,
horticulture and private plantations throughout the district
(except the areas designated as protected areas) across all
agro-climatic zones (coast, ghats, plains, and transition
zones).
Figure 3: Dynamics in Land use, Forest cover and Forest
Fragmentation across the West flowing rivers of Central
Western Ghats
River basin wise land use analyses (Figure 4) reveals that
anthropogenic activities involving monoculture (both forest
plantation and horticulture) plantations and exploitation of
timber in the Aghanashini river basin have led to the
decline in the forest cover from 86.08% (1973) to 50.65%
(2018) followed by river basins of Kali (37.8%), Gangavali
(37.7%) and Sharavati (23.3%).
Evergreen forest cover in Aghanashini riverscape has declined
from 72.15% (1973) to 24.09% (2018), while moist deciduous
forest cover has increased from 9.79% to 25.76% during this
period. While there has been a sharp increase in
agricultural activity from 4.46% to 16.38% in the coastal
regions, on the Ghats and transition zones to the east,
horticulture practices (Arecanut gardens) have increased
from 3.63% to 10.68%, especially along the river valleys and
stream courses. Urban growth has picked up as indicated by
increase in built-up areas from 0.1% to 4.87% in the
proximity of the coast (Gokarna and Kumta) and along the
Ghats (Sirsi). There has been a reduction in the interior
forest cover from 73.28% to 17.78%, with increase in edge
forests (from 8.71% to 19.65%) and transitional forests
(from 1.86% to 8.23%).
Construction of series of dams in the Kali river basin at
Supa, Kodasalli, Kadra, etc.52 has resulted in
loss of forest cover (from 87.26% to 54.24%) and in
particular the evergreen forests (from 61.82% to 30.5%). Due
to the availability of water and lack of appropriate
regulatory mechanism, there have been forest encroachments
in the eastern part of the catchment (near Hubli and
Belgaum) leading to increase in agricultural and
horticulture activities (17.02% to 22.15%). Overall, the
forest cover in Kali river basin has reduced. Infrastructure
activities (Karwar, Hubli – Dharwad) have boosted the growth
of urban areas from 0.39% to 2.95%. All these pressures have
reduced the contiguous native intact forest from 78.95% to
33.2% in the Kali river basin.
Similar level of anthropogenic stress was witnessed in the
Sharavati river basin which has led to the decline in forest
cover (from 61.97% to 47.55%) with the loss of evergreen
forests (from 52.68% to 27.11%) and an increase in deciduous
forests by two fold. Human animal conflicts have increased
due to the disruption of animal movement paths with the
decline of the contiguous intact (interior) forests from
45.88% to 23.97% and loss of fodder, water, etc. with
decline of native vegetation. There has been an increase in
urban spaces (0.45% to 2.05%), and horticulture lands (2.13%
to 15.91%), etc. Also, the decline in agricultural practices
in Sharavati river basin was noticed with the large scale
conversion of paddy fields into cash crop fields like areca
gardens, etc.
Figure 5: Eco-Hydrological Footprint (Water Availability)
across the basins
Figure 6.
Eco-hydrology and forest linkages.
Figure 7: Ecologically Sensitive Regions in Uttara Kannada
District
People’s livelihood and eco-hydrological status
of a catchment: A comparative assessment of
people’s livelihood has been made with soil water properties
and availability of water in the respective catchment. The
result shows that, catchments with > 60% vegetation with
native species has higher soil moisture and groundwater in
comparison to the catchment (of seasonal stream) during dry
spell of the year. The higher soil moisture due to the
availability of water during all seasons facilitates farming
of commercial crops with higher economic returns to the
farmers, unlike the farmers who face water crisis during the
lean season. The study emphasizes the need for conservation
endeavour on maintaining native vegetation in the catchment,
highlighting its potential to support people’s livelihood
with water conservation at local and regional levels. Both
plantation and agricultural crops have been considered for
the valuation in the select catchments of perennial and
seasonal streams. Plantation crops (viz. areca nut, coconut,
banana, beetle leaf and pepper) are the major income
generating products in the catchment of perennial streams. A
total amount of Rs. 3,11,701 ha-1
yr.-1 (year 2009-10) gross average income was
generated from the plantation crops against an average
expenditure of Rs. 37,043 ha-1 yr.-1,
(mainly for plantation maintenance), yielding a net profit
of Rs.2,74,658 ha-1 yr.-1. On the
contrary, for the catchment of seasonal streams, (where both
plantation and rice fields were considered for income
calculation) the average gross income generated was Rs.
1,50,679 ha-1 yr.-1 against
expenditure of Rs. 6474.10 ha-1 yr.-1
for plantation maintenance and field preparation.
Faunal diversity and total economic value: The
presence of contiguous or intact forests with the native
species maintain the natural flow conditions and water
quality. Alteration in the natural flow regime through
construction of reservoirs for impounding water and
releasing as per societal needs has led to an imbalance in
the ecosystem, loss of habitat, alteration in water quality
etc. Altogether 61 fish species from 47 genera and 38
families were recorded from the Kali estuary. Gangavali, has
55 species of fish from 46 genera and 39 families.
Aghanashini has highest diversity of fishes; 86 species
belonging to 66 genera and 47 families, while Sharavati has
lowest with 43 species from 25 genera and 24 families60,99.
This high diversity in Aghanashini estuary is obviously due
to preservation of the relative naturalness of the river,
unaffected by dams or other major developmental projects.
However, shell and sand mining that have intensified in
recent decades, have telling effect on estuarine fish
population and livelihood based on them60.
These four estuaries spreading across 7,549 ha area,
constitute a very important employment sector in the
district, accounting for about 2,092,000 fishing days/year,
benefiting altogether an estimated 3,086 families of
estuarine fishermen, generating 277 days of fishing work per
year and generating an income of Rs. 88,157/ha/year. This is
significant considering income is without any input from
humans except on fishing efforts through human energy alone,
as mechanized fishing is not practiced in the estuaries of
the district. The estuarine area required for fishing was
0.56 ha per head in Gangavali and Aghanashini (both are
without dams), 1.58 ha in Kali and a whopping 4.72 ha in
Sharavati (impacted by series of hydro-electric
projects).
Table 1 lists estuarine faunal diversity with the total
economic value, which highlights the importance of
maintaining natural flows to sustain the estuarine diversity
and also ecosystem goods and services. Natural flows are
regulated in the Kali and Sharavati rivers with reservoirs
built across them for producing electricity at Supa,
Kodasalli, Kadra (Kali) and Linganmakki (Sharavati).
Controlled flows alter the salinity and nutrient levels in
the estuaries, which results in the lowering of goods and
services as evident from the Total Economic Value (TEV) per
hectare. The TEV is 1.2 Million Rupees (Sharavati) and 2.5
Million Rupees (Kali) as compared to 5 Million Rupees per
hectare per year in the Aghanashini or 2.6 Million Rupees
per hectare per year in the Gangavali rivers. Gangavali and
Aghanasini rivers are devoid of reservoirs and the flow in
these rivers are natural. This ecology also has led to
higher diversity of bivalves which consists of about 13
species in Gangavali and 86 species in
Aghanashini65. The study reiterates the need for
maintaining the natural flow regime and prudent management
of watershed to i) sustain higher faunal diversity, ii) to
maintain the health of the water body and iii) to sustain
people’s livelihood with the higher revenues. The study
negates the current decision makers approach with an
assumption ‘Fresh water flowing into the Sea is a waste
of a precious natural resource’, and highlights the
importance of maintaining forests with native vegetation in
the catchment areas to sustain water quality and quantity of
the rivers during all the seasons. The unregulated flows in
rivers can maintain the health and biodiversity in the
downstream regions also including coastal waters, wetlands
(mangroves, seagrass beds, floodplains), and estuaries.
Table 1: Estuarine faunal diversity and total economic
value(TEV) 65,71,84,100
River Basin |
Dams |
Fishes
(Sp. Count) |
Gastropods / Bivalves (Sp. Count) |
TEV Rs. per hectare per year |
Kali |
6 Reservoirs |
61 |
7 |
2.5 Million |
Gangavali |
Presence of small check dams |
55 |
6 |
2.6 Million |
Aghanashini |
Presence of small check dams |
86 |
7 |
5.0 Million |
Sharavati |
3 Reservoirs |
43 |
2 |
1.3Million |
Citation :Ramachandra T. V., Vinay S., Bharath S., Subash Chandran M. D. and Bharath H. Aithal, 2020. Insights into riverscape dynamics with the hydrological, ecological and social dimensions for water sustenance, Current Science, Vol. 118(9): 1379-1393
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