The main reasons for the water shortage in the north of Qinlin and Huaihai in China are:

Changes in river runoff are affected by seasonal changes in precipitation! Option A focuses on explaining that there is no obvious rainy season and dry season in the precipitation in the north in a year, so the runoff of the northern rivers does not vary much from year to year, but only explains the seasonal distribution of precipitation, indicating that the precipitation in a year is very balanced, there is a fixed amount of precipitation, and there is no excessive difference in the precipitation of the four seasons of the year, and there is no water shortage problem. Item B:

It shows that the accelerated development of industry and agriculture in the north requires a large amount of water for the irrigation of crops, which belongs to agricultural water, and the densely populated north also needs a large amount of domestic water, because of these two reasons, the shortage of water resources in the north has been greatly aggravated, so there will be a "south-to-north water diversion" project. Does that make you know why you didn't pick A? Hope it helps!

1.Less precipitation.

2.Water conservation capacity is poor.

3.The demand for water is large, and the efforts to save water are insufficient.

Runoff varies greatly, and the net flow of rivers varies greatly because precipitation varies greatly, and some rivers freeze and so on. It's a sophomore.,High school geography almost forgotten.,If you don't forgive me.。。。 And b is the man-made cause of water shortage in the north.

The northern rivers basically have great inter-annual variations in runoff, with floods and droughts, such as the Yellow River, which has floods in summer and even partial interruptions in winter.

A means that precipitation in the north does not vary much from year to year.

This in itself is correct.

However, it is not that there is little change that causes water shortage.

If the seasons change greatly, there is a risk of water shortage.

and the area north of the Huai River in the Qinling Mountains.

It has a temperate monsoon climate.

The precipitation is still much worse than that in the south of the Yangtze River.

Plus the dense population and other reasons.

There is also a waste of water resources that is also an important factor in water scarcity.

The total amount of water resources in China is quite large, but the per capita share is very low, about 1 4 The regional distribution of water resources in China is significantly uneven, which is manifested in the characteristics of "more in the east and less in the west, more in the south and less in the north" The southern part of China accounts for about 40% of the total collapse area of the country, but its diameter and fuel flow accounts for more than 80% of the total runoff of the country. The north accounts for about 60% of the total area of the country, but less than 20% of the total runoff of the country, and the water shortage in the arid areas of the northwest is particularly serious The cultivated land in the Yellow River, Haihe River and Huaihe River basins accounts for more than 38% of the country's cultivated land, and the population is dense, the industry is developed, and the water demand is large, and the water resources account for about 6% of the country

Therefore, d