I noticed from your initial post that the rains only occur a few times a year and they bring ~ 16,000 cm3 (4,226,752 gallons). You want to capture ~ 4,000 cm3 (1,056,688 gallons). Chris posted a link regarding Sepp Holzers "monks", but I think you will have to deal with a lot more water flow than a typical "monk" can handle. Basically your pond will have to handle very high flow rates at very sporadic intervals. You need a design that can send ~ 25% of the flow to the pond and the remaining 75% is diverted safely around the pond so that the ponds "spillway" is probably never utilized.
With clay like you showed in the photo, I doubt that infiltration losses will amount to much. What about evaporation? Where (generically) will this project be located?
Have you contemplated the equipment needed to perform this project? This is a fairly large earth moving project at 4,000 cm3 (5,231 yd3)?
I have more questions, but answers to these will help direct future responses.
"cm3" is an abbreviation for 'centimetres cubed'. You probably mean cu.m or m3 or m³ since you're talking about cubic metres.
PS: Just in case you weren't aware already, you can uncheck 'Disable HTML in this message' below the editing box and type in ² to generate a ² or ³ to generate a ³ (e.g. 4000m³ displays as 4000m³) — useful superscripts for areas and volumes.
PPS: If you end up with unwanted smilies in your post, just check 'Disable smilies in this message' below the editing box. This will happen if you have an area or volume within brackets because the last two characters — ;) — are otherwise converted to a winking smilie.