hydrological ysis and calculation is to predict the probability distribution of the hydrological variable .
hydrological forecasting is to predict the scale and time course of a hydrological variable .
the occurrence and development of hydrological phenomena are accidental, therefore, their occurrence and changes .
water is a type of .
the reason for making water resources regenerative is of natural.
the check flood level and design flood level of the three gorges project on the yangtze river are .
in natural world, the hydrological cycle between land and sea is called .
the hydrological cycle in nature makes water resources .
we can trace many causes for the occurrence and development of hydrological phenomena. therefore, the change in hydrological phenomena .
the drainage area refers to which is above a certain cross section of the river.
if there are two heavy rains occured in a certain river basin, expect the occurance location, one occured in the upstream and the other in downstream, other conditions are the same. then, the peak flow at the exit section of river basin caused by the upstream one will be than the one caused by the downstream.
the condition for the formation of heavy rain is .
the characteristics of convective rainfall are .
for relatively dry soil which is under sufficient water supply conditions, the physical process of infiltration can be ided into three stages, which are in turn.
is the main factor determining the stable infiltration rate of soil.
the total evaporation of the watershed includes .
the amount of the daily water surface evaporation, observed by the e601 water surface evaporator, and of the daily water evaporation of large water body is (has) .
the process of basin confluence mainly includes .
the amount of floods formed by the net rain depth of rainfall in river basin should be quantitatively .
when the water level does not change much in a day, should be applied to calculate the daily average water level.
in the hydrological test, is the key to determine the flow through a cross section in river channel .
when using a flow meter to measure the velocity of a point, the time required for each measurement should be .
measuring the flow velocity at a certain point with a flow meter, actually is to measure the of the flow meter at that point.
when a hydrologic station is affected by flood fluctuations, the relationship curve of water level and flow .
the relationship of water level and flow in a hydrologic station is a single curve. when the messuring cross section is silted, .
which of the following is wrong about the rainfall factors? .
which question does not need to be answered in runoff calculation： .
infiltration-excess runoff only yields surface runoff, and the runoff condition is：
which one is not the three elements of the unit hydrograph? .
hydrologic phenomenon is a natural phenomenon, which of the following property does it have?
what is an event that may or may not occur in a randomized trial?
the normal frequency curve is a drawn on the frequency grid paper.
the second central moment is .
which of the following aspects is correlation ysis mainly used in hydrologic ysis calculation?
runoff is formed by precipitation, so the relationship between annual runoff and annual precipitation is which of the following?
generally, the influence of human activities on the average annual precipitation in the basin is
human activities (such as the construction of reservoirs, irrigation, water and soil conservation, etc.) indirectly affect the annual runoff by changing the nature of the underlying surface，which generally causes the
through the ysis and calculation of the measured annual runoff data, the annual runoff mean value and departure potential coefficient of the two rivers a and b are obtained as follows: a river: =100, =0.42; b river: =500, =0.25, by comparing the two rivers, it can be seen that
in the ysis and calculation of design annual runoff, the purpose of extending short series data to long series data is to
when using the contour map of annual average runoff depth to calculate the annual average runoff of all watershed, its value is equal to
in the selection of typical years, when more than one typical year is selected, irrigation engineering should select
in the selection of typical years, when more than one typical year is selected, should be selected for hydropower projects.
in the calculation of frequency, when referring to the dry water flow of a certain recurrence period, it is usually
design flood refers to
the three elements of design flood are
smoothing the amplified design flood is based on
reservoir inflow flood includes
the period of design flood stage is determined by
in the evaluation of prediction, which the following one is correct:： .
the operating zone that needs to be reduced in the following figure is:
the flood limiting water level is determined by stages because in each stage of the flood season: