The Himalayas and the Western Ghats are both mountain ranges, but there are several factors that contribute to the more frequent occurrence of landslides in the Himalayas compared to the Western Ghats. Additionally, the absence of delta formation by rivers in the Western Ghats can be attributed to specific geological and environmental conditions.

Causes for more frequent landslides in the Himalayas:

1. Tectonic activity: The Himalayas are located in a seismically active region. The collision between the Indian and Eurasian tectonic plates is ongoing, leading to constant geological forces that contribute to the instability of the mountain slopes and an increased likelihood of landslides.

2. Steep and rugged topography: The Himalayas are characterized by steep slopes, deep valleys, and rugged terrains. This rugged topography makes the slopes more prone to erosion and instability, enhancing the chances of landslides.

3. High precipitation and snowfall: The Himalayas receive high amounts of precipitation, including heavy monsoon rains and intense snowfall during the winter months. The excess water weakens the soil and rocks, making the slopes more susceptible to landslides.

4. Glacial melting: The Himalayan region contains numerous glaciers, which are melting due to global warming. The melting ice and increased water runoff from glaciers contribute to an increase in landslides by further destabilizing the slopes.

Causes for the absence of delta formation in Western Ghats rivers:

1. Relief and slope: Unlike the Himalayas, the Western Ghats have relatively gentle slopes and less rugged terrains. The rivers flowing through the Western Ghats do not encounter the steep gradient required for significant sediment deposition, which is necessary for the formation of deltas. The sediments carried by the rivers tend to get distributed and deposited along the lower slope areas instead.

2. Shorter river courses: The rivers in the Western Ghats tend to have shorter courses compared to those in the Himalayas. The shorter courses limit the distance over which the rivers can transport sediments and therefore restrict the opportunities for delta formation.

3. Type of rocks and geology: The Western Ghats are predominantly composed of hard and resistant rock formations, such as granite and gneiss. These rocks erode at a slower pace compared to the softer rocks found in the Himalayas. As a result, the erosion in the Western Ghats is not sufficient to create significant sediment loads required for the formation of deltas.

4. Coastal dynamics: The Western Ghats have a relatively narrow coastal plain. The low gradient coastal areas do not offer extensive opportunities for the rivers to build deltas, as the sediment transport is influenced by the balance between the river inputs and coastal currents.

Therefore, the combination of geological, topographical, and environmental factors contributes to the more frequent occurrence of landslides in the Himalayas compared to the Western Ghats. Similarly, the absence of delta formation in Western Ghats rivers can be attributed to the specific geological characteristics and limited sediment transport opportunities in the region.

Landslides in the Himalayas vs. Western Ghats

Causes for more frequent landslides in the Himalayas:

• Tectonic Activity: The Himalayas are a young, geologically active mountain range formed by the collision of the Indian and Eurasian tectonic plates. This constant pressure creates unstable slopes prone to landslides.
• High Altitude and Steep Slopes: The Himalayas are much taller than the Western Ghats, leading to steeper slopes and increased gravitational forces that contribute to landslides.
• Heavy Rainfall: The Himalayas receive heavy rainfall during the monsoon season, saturating the soil and increasing its weight, making slopes more susceptible to landslides.
• Glaciers and Permafrost: The presence of glaciers and permafrost in the Himalayas adds further instability to the slopes. Melting glaciers can trigger landslides, and permafrost thawing can weaken the ground.
• Deforestation and Human Activities: Deforestation and human activities like road construction and mining can destabilize slopes, increasing the risk of landslides.

Western Ghats:

• Older and More Stable: The Western Ghats are geologically older and more stable than the Himalayas, with less active tectonic forces.
• Lower Altitude and Less Steep Slopes: The Western Ghats are significantly lower in altitude than the Himalayas, resulting in gentler slopes and less gravity-induced instability.
• Seasonality and Rainfall: While the Western Ghats receive heavy rainfall during the monsoon season, the rainfall is generally less intense and concentrated over a shorter period than in the Himalayas.
• Dense Vegetation: The Western Ghats have dense forests and vegetation cover that provides a natural barrier against soil erosion and landslides.

No Delta Formation in Western Ghats Rivers

• Shorter Rivers: Rivers in the Western Ghats are generally shorter and less voluminous compared to rivers in the Himalayas.
• Steep Gradient: The Western Ghats have a steep gradient, leading to rapid flow and erosion, preventing the accumulation of sediments needed to form deltas.
• Rockier Terrain: The Western Ghats are composed of hard, metamorphic and igneous rocks that erode slowly, limiting sediment transport downstream.
• Strong Coastal Currents: Strong coastal currents along the western coast of India quickly disperse any sediment brought by rivers, hindering delta formation.
• Limited Coastal Plain: The coastal plain along the Western Ghats is relatively narrow, restricting the space for deltas to form.

Therefore, the combination of factors like shorter rivers, steep gradient, strong coastal currents, and limited coastal plain contributes to the absence of delta formation in the rivers of the Western Ghats.

Causes of frequent landslides in the Himalayas compared to the Western Ghats:

1. Tectonic activity: The Himalayas are a geologically active region, with ongoing plate tectonics and faulting, which leads to frequent earthquakes, rock deformation, and instability, increasing the likelihood of landslides. In contrast, the Western Ghats are a relatively stable region with less tectonic activity.
2. Steep slopes and relief: The Himalayas have very steep slopes and a high relief, which increases the likelihood of landslides. The Western Ghats have gentler slopes and lower relief, making landslides less frequent.
3. Heavy rainfall: The Himalayas receive very heavy rainfall, especially during the monsoon season, which saturates the soil and increases the likelihood of landslides. The Western Ghats also receive heavy rainfall, but the intensity is generally lower than in the Himalayas.
4. Deforestation and human activities: The Himalayas have experienced significant deforestation and infrastructure development, leading to soil erosion, increased runoff, and increased risk of landslides. The Western Ghats have relatively less human disturbance and deforestation.
5. Soil composition: The Himalayas have a higher proportion of loose, unconsolidated sedimentary rocks, which are more prone to landslides than the harder, more resistant rocks of the Western Ghats.

Why rivers of the Western Ghats do not form deltas:

1. Shorter river lengths: The rivers of the Western Ghats are generally shorter and have fewer tributaries, which reduces their sediment-carrying capacity and the likelihood of forming deltas.
2. Steeper gradient: The Western Ghats have a steeper gradient, which means that rivers flow more rapidly, carrying sediment straight into the ocean rather than depositing it near the coast, where a delta might form.
3. Higher ocean energies: The Arabian Sea, where the Western Ghats rivers drain, has higher ocean energies than the Bay of Bengal, where the Himalayan rivers drain. This means that the sediment carried by Western Ghats rivers is more likely to be dispersed or transported away from the coast, rather than accumulating to form a delta.
4. Less sediment supply: The Western Ghats have lower sediment yields due to their geology and relatively lower rainfall compared to the Himalayas, which reduces the amount of sediment available to form deltas.

These factors combined explain why landslides are more frequent in the Himalayas than in the Western Ghats, and why the Western Ghats rivers do not form deltas.