November 15, 2021 has been adopted for the remote sensing estimate of the start of the zero flow period at the Ruaha Park Headquarter (Msembe Bridge). The status of the Ruaha River Flow at the Msembe Bridge (top right) for November 14 and 19, 2021 are illustrated by the 5 meter Sentinel image in the middle and on the right, respectively.
Alert Phase 3 with drainage dropping under 3cumecs at Nyaluhanga not yet possible to assess remotely.
Post with conclusion based on mix up of satellite images removed.
Floating Reed instead of Zero (Drainage) Flow in Ruaha?
The absence of the “blockage” or exposed riverbed on November 17, 2021 continuing up to November 24, 2021 (image above) suggests that the dark Ruaha River section has been floating reed. (click on image to enlarge)
Post has been removed conclusions based on mix up of satellite images
Comparison of confirmed zero drainage just downstream of Nyaluhanga Gauge Station on November 6, 2019 shows that exposed riverbed sediments color red on near infrared Sentinel 2 image like floating reed. The natural color is on the left and the near infrared image on the right. (click on image to enlarge)
Third Alert November 4, 2021 (suspected)
Confirmation sought for zero drainage downstream of Nyaluhanga. On November 9, riverbed exposed 1.3km downstream of first observation see previous image of November 4, 2021. Also very low levels at Park Headquarters support critically low flow.
Alert 3 Critical Low Drainage Usangu Rice at Nyaluhanga
Critical low drainage flow on October 28, 2021 at Nyaluhanga Gauge Station defined by the drying of the tributary under the magnifier. According to rating curve the drying of the tributary corresponds with a flow at the gauging station of ~8.3cumecs.
Second Alert August 31, 2021
Compare first zero flow event 2020 in Ruaha at Mtera (left) with first zero flow event 2021 (right) on same location, on August 31 (visual assessment).
First Alert July 16, 2021
One month before zero flow in Ruaha at Mtera upstream of confluence with Little Ruaha. Compare August 16, 2020 (First Alert 2020) with July 17, 2021 (First Alert 2021)
