There are many factors that affect the occurrence and the degree of sampling and nonsampling error.

In this paper,some hotspot issues on the application and theory of survey sampling are reviewed,including sampling design and inference,the analysis of non-sampling errors and small area estimation.

This paper was focused on deriving the B nomogram of L-moments method,which was used to estimate the sampling errors in frequency analysis.

The results show that the former sampling error becomes much less than the latter.

The operation scheme defined by the model has been applied to five hydropower stations on the upper reaches of the Yellow River according to various possible inflows for the analysis of expected energy output and sampling error.

Aiming at the sample error and its poor representativeness, this paper introduces several insertoffset methods of runoff for water resources evaluation combining with the properties of hydrology in Baicheng area by the theory of hydrology.

This paper mainly discusses principle and application of sample error in hydrological analysis, and analyses an example.

The correlation degrees between subjects in multi-subject sampling survey are discussed in three cases, in view of every condition, the relevant sample orgainzation and the calculating methods of target variable, sample size and sample error are put forward in this thesis.