Dear Luan,

Some articles may help:

Article Urban hydrologic trend analysis based on rainfall and runoff...

Article Time Series Analysis of Hydrologic Data for Water Resources ...

https://rmgsc.cr.usgs.gov/outgoing/threshold_articles/Burn_Elnur2002.pdf

Dear Ahmed Elwan ,

I have just had a quick look at your recommended links and found these two links are especially useful for newbies in hydrology.

https://cran.r-project.org/web/packages/trend/index.html

Article Change detection in hydrological records—a review of the met...

Thank you very much for your help.

I want to provide more info about my question

My task is about describing the trend of water level and flow discharge in the Mekong Delta of Vietnam. I'm supposed to use time series data from 1998 to the most recent period with available data. It is also very likely that I can get access to data from 1980. I did not know that trend describing is different to trend detection. Is trend detection is about looking for specific patterns in time series data. If it is so, it is also very interesting because there are many factors that can have great impacts on hydrological features of the Mekong River including dyke heightening, upstream dam construction and decreasing of inflow due to climate change. Right now, I'm still looking for a direction to develop my research. I'm very open to any suggestion about research objectives and methodologies. I'm also quite skillful in Python which might be useful for the task.

Dear Hong Luan Luan, your work is interesting and I would like to have updates of your research.

Thanks

Dear Rizwan Waheed,

Yes, I will update the result but not very frequently in this phase for I'm still brainstorming and grasping knowledge which is quite far from my expertise.

Thank you for your consideration

You can do it on excel or R software

Dear Drlatief Ahmad

Yes, Ahmad. I'm actually trying to develop a Python script to deal with the job. Thank you for your advice.

For temporal trend analyses of hydrologic quantities such as precipitation and runoff, the nonparametric Spearman Rank test and Kendall-Tau test have each been recommended by statisticians. Software that runs these tests is commonly available (google the test names), and quick & easy to do, and are well-accepted tests for trend. This is a good start; after these two tests you might also want to explore more sophisticated statistical tests and measures that are the best match for your data types and the objectives of your investigation, perhaps within a time-series modeling framework.

Hong--in order to separate the possible effects of climate change & land use change from the effects of dams and diversions (and other such anthropogenic factors), it is likely that you will need to work with the data from flow gages, dam storage and release of water, and diversions ( all in units of water volume or volume/time) to develop datasets of 'unimpaired' flow; i.e. flow that would have occured in the river if the upstream dams and diversions were not present. This unimpaired flow may exhibit long-term trend due to climate change and/or land use change (several decades of data may be needed for this, as there may be weather teleconnections in your study area with the PDO or other decadal-scale natural oscillations). Separating the effects of climate change and land use change on streamflow can get more complex, here you may need to use whole catchment water mass balance approaches.