Landscape Connectivity in Kosi-Gandak Interfan

Key Concepts

1. Hydrologic Connectivity:
  - Spatial-temporal linkages between landscape units
  - Controls sedimentation rates and ecological functions
  - Harvey (2002), Jain and Tandon (2010)

2. Disconnectivity Drivers:
  - Embankments and transportation infrastructure
  - Changing land-use patterns
  - Groundwater overexploitation

Anthropogenic Pressures Impact Assessment

Land Use Changes:

• 78% wetland conversion to agriculture (2006-2023)
• Double cropping in marginal wetland areas

Infrastructure Effects:

• East-west highways disrupting north-south drainage
• Railway embankments blocking natural channels

Water Management:

• Groundwater depletion (2.1m/year decline)
• Surface water diversion for irrigation

Flood Dynamics Analysis

Connectivity Indices (2006)

• Pre-Monsoon IC Formula: IC = -3.0174 * NDVI + 1.372
• Post-Monsoon IC Formula: IC = -2.4888 * NDVI + 1.329
• Pre-Monsoon r²: 0.972
• Post-Monsoon r²: 0.987

Key Findings

Embankment Breaching:

• 2007 Burhi Gandak breach reset system connectivity.
• Created new sediment distribution patterns.

Vegetation Impact:

• C-factor ranges: 0 (vegetated) to 1 (barren).
• NDVI-based regression limitations:
  • Cannot account for management practices.
  • Ignores senescent vegetation.

Mitigation Strategies

Recommended Measures

Restoration:

• Reconnect 35 priority channels.
• Create buffer zones around Kaabar Tal.

Policy:

• Wetland protection legislation.
• Sustainable groundwater extraction limits.

Monitoring:

• High-resolution hydrological sensors.
• Seasonal connectivity mapping.

Hydrological connectivity patterns in Kosi-Gandak interfan (2006)