Bound by the river – modelling the impact of water availability on human-wildlife coexistence.

Abstract

Throughout this century, an unprecedented decline in biodiversity loss has been witnessed worldwide. Animal habitats have been increasingly encroached upon, transforming into urban landscapes and imperilling numerous wildlife. Therefore, preserving natural habitats is essential for maintaining critical feeding, breeding, and nesting grounds to curb species extinction. This has resulted in allocating land for environmental protection, such as buffer zones and national parks designated as protected areas. However, as climate change becomes a constant factor leading to changes in rainfall patterns, water sources that feed into protected areas and buffer zones are declining. Rivers that once fed into forest ecosystems are now the primary source of hydropower and irrigation projects. This shift raises concerns about the repercussions of water scarcity in natural habitats and the impact on the coexistence of humans and wildlife. To investigate the impact of water scarcity on natural habitats and human-wildlife coexistence, we utilize an agent-based model to investigate the interplay between water availability and coexistence within a buffer zone. Our study draws from empirical data gathered at Bardia National Park (BNP) and its buffer zone in Nepal. Covering an area of 968 sq km, the National Park houses 125 tigers and is complemented by a 507 sq km buffer zone. The buffer zone is distributed into 19 districts with a human population 116,000 living alongside the national park. A large portion of this population consists of farmers. The Karnali and Babai River, a pivotal water source for wildlife and surrounding communities, is a natural boundary between animals and local populations. The agent-based model illustrates the intricate temporal and spatial interactions between agents—tigers, rivers, and communities—mapping their migration patterns in response to fluctuating water levels resulting from altered rainfall patterns. This model is instrumental in: including a diversity of agents with specific characteristics and attributes, estimating long-term consequences of local interactions and behaviours, establishing emergent properties (such as territories and conflict) that arise from water scarcity and co-creating integrated water management approaches for increasing water availability for communities and animals.  Over the past decade, both rivers have experienced a decline in water discharge, resulting in a dried riverbed dissolving the natural barrier between humans and wildlife.  Declining rainfall has led to dwindling water sources for irrigation, forcing farmers to look for alternative sources of sustenance. People venture into forests for fodder and natural reeds; meanwhile, lack of water forces wildlife into communities for prey and water. Prey march into grazing fields inside communities, and tigers follow their prey. As the water availability changes, the tigers shift their territories, often venturing into farms. Increasing overlapping of territories over a shared space and resource increases human-wildlife conflicts. The river acts not merely as a boundary but as a vital resource that maintains a spatial equilibrium, keeping these two species in their spaces bound and preventing conflict.  Our research addresses the following question: How to analyze the impact of water availability on human-wildlife coexistence effectively?