[:en]Ramani Huria and The World Bank are trying to understand the best way to calculate elevation in Dar es Salaam so that elevation measurements can be integrated into current flood models. Elevation will add a 3D dimension to flood maps which will improve understanding of water flow and help with flood projections. Measuring elevation requires a series of complicated measurements.

At the end of April 2018, three Civil Engineering students from Delft University of Technology in the Netherlands – Huck, Detmar and Martijn – arrived in Dar es Salaam to build cheap and practical devices to measure elevation. They will be spending two months in Dar es Salaam to work with Ramani Huria, a community mapping project. They believe the RH team is a very motivated team of young people that  can make community mapping a real and usable source of open data, and they have realized how important and difficult it is to have an accurate and up to date map of such a fast growing city.

Their project objective is to generate elevation readings which are as accurate as possible using temperature and barometric pressure. They will do so using an arduino combined with a Bosch BMP280 inside a watertight box. The goal is to cancel out the noise and errors from the sensors to get an accurate and usable elevation reading to implement and integrate into OpenStreetMap.

This is the first time that they have worked with the BMP sensors so it is a new experience for them to trial how these sensors react within an urban environment. If they succeed in doing this, it will be possible to create an accurate elevation model of a big city using very cheap utensils.

The ultimate goal of Ramani Huria is to accurately be able to measure elevation so as to produce the city flood model using cheap methods and being able to replicate this process in other cities of Africa if they’re need it.

On the 24th May, the results of the Arduino experiments to date were shared at the Humanitarian Development Innovation Fund Innovation Week at Buni Hub.  

Workshop Breakout Session

From experiments so far, many of the environmental noises such as sun, wind and rain have been inspected and can now be taken into account. The absolute error of each sensor is now known and can be calibrated to one point, which has to happen every time a measurement is taken. More time will be needed to fully understand the relative error, but there are now even more filters that have been discovered to minimize this error. In the upcoming weeks the Ramani Huria team, led by the students from Delft, will begin field experiments using an android app which is able to read the arduino and sensor. The app already consists of a IIR filter (infinite impulse response) which filters the measurements to make the data more workable. The next task will be a server that collects all the data of those phones to a platform so these can be used easily and can be looked into at any time of the measurement. Every day, the potential for cheap, locally made devices to determine accurate elevation levels increases. These measurements will contribute to more accurate flood models and mitigation plans.  

 [:sw]Ramani Huria na Benki ya Dunia inajaribu kutafuta njia nzuri ya kupima mwinuko katika jiji la Dar es Salaam ili kuiunganisha na kielelezo cha mafuriko (flood model) ambacho kinaandaliwa. Kupima mwinuko kunahita mfululizo wa vipimo vigumu.

Mwishoni mwa mwezi wa nne 2018. Wanafunzi watatu wa uhandisi kutoka chuo kikuu cha teknolojia cha Delft Uholanzi- Huckleberry, Detmar and Martijn- waliwasili Dar es salaam ili kutengeneza vifaa nafuu/rahisi za kupima mwinuko. Watachukua takribani miezi miwili kufanya kazi na timu ya Ramani Huria. Wanaamini Ramani Huria ni timu yenye vijana wanaojituma na wanaweza kufanya Ramani za kijamii kuwa halisi na kuhamasisha utumiaji wa taarifa huru, na wanaelewa umuhimu na ugumu uliopo katika kupasa ramani sahihi hasa katika jiji linalokua kwa kasi kama Dar es salaam.

Lengo la wanafunzi hawa ni kutengeneza madhubuti kifaa kinachopima mwinuko kwa kutumia joto na mgandamizo wa barometa. Wanafanya hivyo kwa kutumia Arduino iliyounganishwa na kifaa cha Bosch BMP280 inside a watertight box. Lengo ni kuondoa usumbufu wowote kwenye sensor na na kupata mwinuko sahihi unaoweza kutumika na kuingizwa kwenye OpenSteetMap.

Hii ni mara yao ya kwanza wanafanya kazi na BMP sensors hivyo ni uzoefu wao wa mara ya kwanza kwa wao kujaribu hizi sensor na kuona jinsi gani hizi sensor zinaweza kukabiliana na hali ya mazingira ya mjini. Kama wakifanikiwa kwenye hili itawezekana kutengeneza kielelezo cha mwinuko kwenye mji mkubwa kama Dar es salaam.

Lengo kuu la Ramani Huria ni kuweza kutengeneza mbinu ya kupima mwinuko wa jiji la Dar es salaam kwa kutumia njia rahisi na pia uwezekano wa kutumia njia hii kwenye majiji mengine ya Africa kama watahitaji.

Tarehe 24 May, majibu ya majaribio ya Arduino yalionyeshwa kwenye wiki ya ubunifu iliyo andaliwa na mfuko wa maendeleo ya kibinadamu. (Humanitarian Development Innovation Fund)

Maonyesho kwenye warsha

Kutokana na majaribio yaiyofanywa hadi sasa sababu nyingi za mazingira kama jua upepo na mvua vimeonekana ni vitu vinavoweza kuangaliwa kwa ukaribu.Hitilafu kamili ya kila sensor sasa inajulikana na inaweza kuangaliwa kwa pointi moja, ambayo lazima itokee kila wakati kipimo kinapochukuliwa. Timu ilielezea kuwa kosa tegemezi linahitaji muda mwingi zaidi kuelewa na kutatuliwa, lakini sasa wanagundua mbinu zaidi ambazo zinafanya kazi na zinaweza kutumika ili kupunguza hitilafu hii. Katika wiki zijazo timu ya Ramani Huria, ikiongozwa na wanafunzi kutoka chuo cha teknologjia Delft, itaanza majaribio kwa kutumia programu ya simu ya Android inayoweza kusoma Arduino na sensor. Programu tayari imejumuisha kifaa cha IIR (infinite impulse response) – (majibu yasiyo ya msukumo usio na kipimo) ambayo inachuja vipimo ili kufanya taarifa iweze kufanya kazi zaidi. Kazi inayofuata itakuwa server inayokusanya taarifa zote za simu hizi kwenyesehemu moja ili ziweze kutumiwa kwa urahisi na zinaweza kuonekana wakati wowotekipimo kilipochukuliwa. Washiriki katika warsha walivutiwa na uwezekano wa vifaa vya bei nafuu, vilivyotengenezwa ndani ya nchi kuongeza viwango vya kutosha katika kuchangia kwenye kupata taarifa bora ya mafuriko na hatua za kuyapunguza.

 [:]