Prema Hettiarachchi

10 Questions 37 Answers 0 Followers

Questions related from Prema Hettiarachchi

How to extract intense rainfalls (e.g., annual maximum rainfall for 24-hr duration) from the historical records of daily rainfalls?

Generally, the daily rainfalls are recorded at fixed time intervals (e.g., from 9 am to 9 am). We can find such records of historical rainfalls for centuries. However, in such records, even the...

21 November 2023 5,702 2 View

What are the criteria to be adopted in sizing the gates of salinity barriers constructed across the rivers drain flood prone areas?

I have a problem of designing a salinity barrier on a river flowing through a large agricultural area, susceptible for flooding, to prevent saltwater intrusion to domestic water supply intakes....

03 November 2023 2,038 0 View

What is the real cause behind the failure of ‘Yala’ (2023) cultivation under the 'Udawalawa' Scheme? Drought, wrong decision or some other?

This question is mainly targeted to Sri Lankan Engineers, Meteorologists, Agronomists and Lawyers. Even the foreign researchers and consultants who familiar with the system (‘Udawalawa’ &...

07 September 2023 8,939 0 View

What are the adverse effects of using freshwater reservoirs for generating solar energy?

Mine is a tropical country which has developed freshwater reservoirs in different eras of the history (new and ancient), mainly for the purpose of irrigation and hydropower. Those reservoirs are...

27 August 2023 5,430 1 View

What are the laws and regulations available for securing riparian rights of water in river systems and priority order of water using activities?

Udawalawa is a large reservoir constructed in 1960s, mainly for the purpose of irrigation. Later, around 1990s, hydropower reservoir was constructed at the upstream of the same catchment...

12 August 2023 3,759 2 View

Is there significant influence by missing data on flood frequency analysis?

I have annual maximum water levels of a river station for 60 years from the water year 1959/60 to 2019/20, but there is a period of missing data for five years from 1965/66. Can I take remaining...

02 December 2021 9,227 5 View

How I treat the difference of data extracted from daily observations at fixed time intervals and continuous records in the frequency analysis?

I have hourly rainfalls of a station for the last 7 years and daily rainfalls (9 to 9 am) before that (for 25 years) and want to compute 24 hour rainfall of 50-year Return Period. I noticed...

13 March 2021 4,068 3 View

What are the advantages of using POT method over the extreme value analysis in flood frequency estimates?

I have hourly water levels of a river station which was subjected to 45 floods in a 30-year period. Please recommend the best method (POT or annual maximum) for flood frequency analysis. The data...

04 October 2020 6,004 3 View

What is the possible range of runoff coefficient for tropical rain-forests with sloping terrain?

What is the possible range of Runoff Coefficient (Runoff / Rainfall ratio) of tropical rain-forests with sloping terrain and experience over 2000 mm average annual rainfall? What are the...

13 August 2020 5,952 8 View

Has anyone observed (proved by data) a significant change in rainfall amount / pattern as a result of global warming?

Scientists have observed nearly 1 degree Celsius increase of global mean temperature during the last 100 years and they make different predictions / projections on climate change. Has any...

10 October 2019 8,463 7 View