Logging of forest
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.
Logging and the subsequent denudation of the forest cover increases surface runoff since there is less oppurtunity for rainwater to sink into the ground. .Retarded or supressed infiltration accelerates overland flow production,hastening delivery of rainwater into streams and rivers, the oftentimes the water ends up as floodwater into the ocean, especially for an archipelagic country like the Philippines.
Forest denudation also deprives recharge of groundwater aquifers since there is less oppurtunity for water to linger in the ground surface to infiltrate according to the infiltration capacity of the soil.
There are secondary factors in logging activities that can degrade water resources. The construction of roads in logging area can cause sediment production and the movement of sediments into water sources especially surface waters. Logging also modifies the terrain and soil conditions may cause landslides in the worst case and soil erosions in the least case, thus another oppurtunity for sediment production.
Kaingin(slash-and-burn)
The kaingin farming practice refers to burning and clearing (by slashing)of wild shrubs or trees to give way to crop farming in the upland forest area. When these areas are planted with crops, soil erosion can be stopped if not minimized.Unfortunately, a lot of farmers do not necessarily own these lands , so only during planting season do they come and randomly select areas to farm.
Mining activities
Mining involves the movement of large amounts of earth,soil or rocks; the release of acids,heavy metals or other chemicals being mined or incidentally mind; the use and handling of chemicals in the mining process ; and use of large quantities of water in the mining operations and subsequent return or recycling of these wastewater to water sources. Improper