The correct answer is D. All of the above.
If the water table is comparatively high, the irrigation canal becomes useless due to large amount of seepage, water logging of the cultivated areas, and uncertain water demand.
Seepage is the flow of water through the soil and into the groundwater. When the water table is high, there is more water in the soil, which can lead to more seepage. This can cause problems for irrigation canals, as the water can seep into the canal and make it unusable.
Water logging is a condition in which the soil is saturated with water. This can happen when there is too much rain or irrigation, or when the water table is high. Water logging can damage crops and make it difficult for plants to grow.
Uncertain water demand is a problem when the amount of water that is needed for irrigation is not always known. This can happen when the weather is unpredictable, or when there are changes in the amount of water that is available. Uncertain water demand can make it difficult to plan for irrigation, and can lead to problems such as water shortages or waterlogging.