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 plantations^82,95, 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 families^60,99. 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