Double Mass Analysis in Hydrology

This tutorial covers the use of double mass analysis to assess changes in rainfall data at a specific station due to environmental changes. It explains how to check data consistency, identify regime changes, and adjust records accordingly. The tutorial also demonstrates calculating cumulative and average annual rainfall using Excel, plotting data, and analyzing results to understand the impact of environmental changes on hydrological data.

What is the primary purpose of using double mass analysis in hydrology?

• To calculate the average wind speed.

• To determine the soil composition.

• To check the consistency of rainfall records.

• To measure the temperature changes over time.

Which of the following is a reason for changes in the hydrological environment of a station?

• Removal of a forest.

• Installation of solar panels.

• Construction of a new road.

• Increase in local population.

How can you calculate cumulative rainfall for a station using a spreadsheet?

• By using the SUM function.

• By using the AVERAGE function.

• By manually adding each year's rainfall.

• By using the equal sign and dragging the formula.

What is the purpose of plotting cumulative rainfall data?

• To create a colorful chart.

• To visually identify changes in rainfall patterns.

• To compare temperature variations.

• To calculate the total rainfall.

Which color is used to format the major grid lines in the graph?

• Red

• Blue

• Green

• Black

What is the adjustment factor used for in double mass analysis?

• To determine the wind speed.

• To change the color of the graph.

• To calculate the average temperature.

• To adjust the rainfall data for consistency.

How is the slope of a line calculated in the context of double mass analysis?

• By dividing the change in rainfall by the change in time.

• By subtracting the initial rainfall from the final rainfall.

• By multiplying the rainfall by the time period.

• By adding the rainfall values together.

In which year did the change in rainfall regime occur according to the analysis?

• 1970

• 1960

• 1980

• 1952

What is the average annual rainfall for the period 1952 to 1970?

• 24.72 cm

• 30.50 cm

• 18.90 cm

• 27.65 cm

What does the final plot between cumulative adjusted data and 18 station cumulative data show?

• A circular pattern.

• A fluctuating line.

• A straight line indicating consistency.

• No discernible pattern.