--- title: "Free community tools: season condition and flood impact for any district" description: "Choose your district and see whether this season's rain and crop growth are better or worse than usual, or where it flooded and who lives there." url: https://www.technicalgis.com/articles/community-tools-season-and-flood/ author: TechnicalGIS Team publisher: TechnicalGIS (https://www.technicalgis.com/about/) published: 2026-10-29 updated: 2026-10-29 language: en-GB --- # Free community tools: season condition and flood impact for any district > Choose your district and see whether this season's rain and crop growth are better or worse than usual, or where it flooded and who lives there. ## Key takeaways 1. Two free tools answer local questions for a district chosen from a list: whether the season is drier or less green than normal, and where it flooded and how many people live in the flooded area. 2. Each answer gives the figures, a chart or map, a one-line reliability rating and the data credits, and you can share it by link, print it on one page or download it as CSV. 3. In Marsabit, Kenya, rainfall for October to December 2022 was 54% of normal and vegetation was the weakest for those months since records began in 2001. 4. In Feni, Bangladesh, radar showed about 39 km² newly flooded in late August 2024, and about 4,400 people live in that area. The [community tools](https://www.technicalgis.com/community-tools/) answer two questions that local groups ask all the time. Choose your district and [Season condition](https://www.technicalgis.com/community-tools/season-condition/) tells you whether this season’s rain and crop growth are better or worse than usual. [Flood impact](https://www.technicalgis.com/community-tools/flood-impact/) shows where it flooded and how many people live there. Both are free, run in a web browser on a phone, and give you a short answer in plain words rather than a dataset to process. If you’re advising farmers about a single field rather than a whole district, try [Farm check](https://www.technicalgis.com/farmers/): tap a spot and see whether the rains have started, the next 10 days’ weather and how green the crops are. ## How the tools work There’s no map to draw on. Choose a country, then a district, province or county from the list. More than 52,000 districts in 200 countries and territories are included, with boundaries from [geoBoundaries](https://www.geoboundaries.org/). Then choose the period. For season condition that’s one, three or six months and the month it ends. For flood impact it’s the date of the latest satellite pass you want to include. The tool tells you how long it will take before you start: about a minute for season condition, one to three minutes for flood impact. Every answer has: - a one-sentence headline; - the figures behind it, with a chart or map; - a one-line rating: good guide, fair guide or rough guide; - the data sources and credits; - the date and a link you can share. You can print any answer on one A4 page, save it as a PDF or download the figures as CSV. Answers are kept for 90 days, so anyone who asks the same question in that time gets it straight away. ## Season condition: Marsabit, Kenya, October to December 2022 Marsabit County in northern Kenya has two rainy seasons, the long rains from March to May and the short rains from October to December. By August 2022 the regional climate centre was forecasting a fifth failed season in a row across the eastern Horn of Africa, with more than 50 million people already short of food ([UN News, August 2022](https://news.un.org/en/story/2022/08/1125552)). ![Season condition answer for Marsabit: rainfall bars for October to December in each year since 1991 with 2022 below the usual band, and a vegetation line since 2001 that reaches its lowest point in 2022](https://www.technicalgis.com/_astro/season-marsabit-2022.Ct5sNC61_1PY0vS.webp) _The season condition answer for Marsabit, October to December 2022. Rain was below usual, and plants were the least green for these months in the record._ The answer: rain in Marsabit was below usual, and plants were far less green than usual. - **Rain** was 86 mm against an average of 161 mm, 54% of usual. Only seven of the thirty years from 1991 to 2020 were drier. - **Greenness** (NDVI) averaged 0.17 against a usual 0.28: the lowest for these months since the MODIS record began in 2001. The two together tell the story. On rain alone this was a poor season but not an exceptional one. Greenness shows the effect of several failed seasons in a row: pasture hadn’t recovered from earlier droughts, so a below-average season left the land barer than at any time in twenty years. Cropland covers less than 1% of the county, so greenness was measured on all vegetated land, and the answer says so. It was rated a fair guide. That matches what was reported on the ground. The [Kenya Drought Response Plan for 2023](https://reliefweb.int/report/kenya/kenya-drought-response-plan-january-december-2023-issued-january-2023) records five below-average rainy seasons in a row and an estimated 2.6 million livestock deaths, and named Marsabit among the counties expected to reach Emergency (IPC Phase 4) by March 2023. [Download the Marsabit answer as a one-page PDF](https://www.technicalgis.com/downloads/community/season-marsabit-2022.pdf) or [the figures as CSV](https://www.technicalgis.com/downloads/community/season-marsabit-2022.csv), or [run it again in the tool](https://www.technicalgis.com/community-tools/season-condition/?d=KEN-1-0025&months=3&end=2022-12). ### How the comparison works Rain comes from CHIRPS version 3, which blends satellite estimates with rain-gauge records. The total for the chosen months is compared with the same months in every year from 1991 to 2020. Greenness comes from MODIS and is compared with 2001 to 2020. Where at least 5% of a district is cropland, greenness is measured on cropland only, so a poor harvest isn’t hidden by forest or grazing land. The result is put into one of five groups, from well below usual to well above usual. ## Flood impact: Feni, Bangladesh, August 2024 In late August 2024, heavy rain and water flowing in from India caused flash floods across eastern Bangladesh. By 30 August, OCHA reported 5.8 million people affected in 11 districts and more than 500,000 sheltering in evacuation centres. Feni was among the worst hit ([OCHA Situation Report No. 2, 30 August 2024](https://www.unocha.org/publications/report/bangladesh/bangladesh-eastern-flash-floods-2024-situation-report-no-02-30-august-2024)). ![Flood impact map for Feni: the district outline with dark blue patches of newly flooded land concentrated in the north, along the border with India](https://www.technicalgis.com/_astro/flood-feni-2024.DosuarCF_Z1Y6wVt.webp) _The flood impact answer for Feni, from Sentinel-1 radar passes on 21 and 28 August 2024. Most of the new flooding is in the north of the district._ The answer: about 39 km² of Feni was under water in radar images from 21 to 28 August 2024, and about 4,400 people live there (between 1,100 and 8,000). - **Flooded area** was about 39 km², 4.4% of the district. The range of 20 to 57 km² comes from counting water more or less strictly. - **The comparison month** was January 2024, picked automatically as the driest month of a normal year in Feni. - **Coverage** was complete: the radar saw the whole district. [Download the Feni answer as a one-page PDF](https://www.technicalgis.com/downloads/community/flood-feni-2024.pdf) or [the figures as CSV](https://www.technicalgis.com/downloads/community/flood-feni-2024.csv), or [run it again in the tool](https://www.technicalgis.com/community-tools/flood-impact/?d=BGD-2-0013&post_end=2024-08-28). ### Why 4,400 is so much lower than the numbers affected The tool counts the people whose homes lie where the radar saw open water. Radar picks out calm open water in fields very well, but water between houses, trees and narrow streets is hard for it to see, and a flash flood can rise and fall between passes. People whose roads, fields or wells were flooded aren’t in the count either. So use the figure to see where flooding was concentrated and to compare districts or events, and use reports from the ground for the number of people affected. ### How the map is made Each radar pass after the flood is compared with passes from the comparison month. A spot counts as newly flooded if it looks like open water after the event and is clearly darker than before. Permanent rivers, lakes and ponds are removed using the JRC Global Surface Water record, and single stray pixels are filtered out. People are counted from the GHSL population map. Tip: set the latest pass date a few days after the flood peaked. The tool looks back 12 days, which normally takes in two or three passes. ## Reuse Every dataset the tools use allows commercial use and sharing of results, and each answer lists its sources and credits. You’re welcome to use the answers in reports, news stories and funding bids: just keep the line “Generated at TechnicalGIS.com” and the data credits. No personal data is used, and no answer identifies an individual home. ## Bigger questions The tools are free and carry no adverts. If your organisation needs a larger area, a run of dates or other measures, [get in touch and choose “Community or NGO project”](https://www.technicalgis.com/contact-the-team/?reason=community). Ready to try it? Open the [community tools](https://www.technicalgis.com/community-tools/) and choose your district. ## Key terms - **Percentile**: Where a value falls among past years. A rainfall total at the 23rd percentile is lower than in about 77% of the comparison years. - **NDVI**: Normalised Difference Vegetation Index, a measure of how green and dense vegetation is, from 0 for bare ground to about 0.9 for dense green growth. - **Synthetic aperture radar**: A satellite instrument that sends microwave pulses and measures the echo. It sees through cloud, and calm open water returns very little signal, so it appears dark. ## Data for this article - [CHIRPS rainfall](https://www.technicalgis.com/data-sources/#src-chirps) · Rainfall estimates from 1981, 0.05° - [ESA WorldCover](https://www.technicalgis.com/data-sources/#src-esa-worldcover) · 10 m land cover used for the cropland mask - [JRC Global Surface Water](https://www.technicalgis.com/data-sources/#src-jrc-global-surface-water) · Permanent water excluded from flood maps - [Global Human Settlement Layer](https://www.technicalgis.com/data-sources/#src-global-human-settlement-layer) · GHS-POP population grid - [geoBoundaries](https://www.technicalgis.com/data-sources/#src-geoboundaries) · District boundaries Licences and formats for each source are listed in the [GIS data sources catalogue](https://www.technicalgis.com/data-sources/). --- Source: https://www.technicalgis.com/articles/community-tools-season-and-flood/